Some are, some are not.
Some red flags about motivation:
* Why would two guys shout 'MAGA country' in Chicago?
Off the top of my head?
1) They were referring to the country in general, or broader areas of the state. It's more puzzling to me that people would assume that the statement could only be an assesment of the city's demographics when it does not mention "city" or "chicago". I live in upstate NY. Our state is pretty blue, so is the city. But there are certainly areas that consider themselves MAGA country.
2) They lived in a particular enclave where the majority of people they spoke to agreed with their political views and gave them a general sense that they were part of a "silent majority" in whatever relevant area they were attempting to address. That's a pretty common scenario and a not uncommon sentiment from Trump supporters over the last couple years.
3) It was more of a rally style mantra with no particular assessment of local politics intended.
4) They were intoxicated or hopped up on anger and it sounded cool to them at the time.
5) Those aren't actually the words they spoke. They may have said "MAGA (blank)" and Smollett and his agent misheard the second word, or press misreported the phrase.
* Why would two guys carry bleach and a noose given that the testimony indicated they were surprised to recognised Smollett?
I don't think the testimony has been so clear that either the assailants were surprised or that the substance was bleach. Even if those two things were facts, a simple answer might be that they were on their way to or from doing laundry. Late night laundromats are common in cities.
Or, the substance wasn't bleach and the cord used as a noose was any of the many random pieces of something that many people carry.
But again, I don't think its clear that they hadn't gone looking for Smollett, in which case any kind of preparation would be possible.
* Why would the attackers be so succinct and informative in their communication, informing their victim in nine short words that they were influenced by Trump, that they were homophobic, that they were racist and that they recognised Smollett from the show 'Empire
This is really the only point that gives me major pause. It's a little on the nose. But as far as motivations go. Certainly people who hate black people, and gay people exist. And shouting epithets during attacks on these groups is something these people seem to do. These groups also tend to be Trump fans. Look at Charlottesville to see footage of people shouting "Jews will not replace us!" and "MAGA!" it's cartoonish, but it certainly exists. Hating on particular celebrities is also pretty darned popular in the white nationalist corners of the internet.
Having all this information shouted in such a succinct package seems a little convenient though, I'll give you that.
* Why would a person be attacked and then wander round for 30 minutes with a phone, yet not call the police, or an ambulance, or notify the security guard?
Its not uncommon for victims of all sorts of attack to not act as a "perfect victim".
1)He may have been shocked or in disbelief.
2)He may, as many people in marginalized groups do, have a severe distrust of police involvement.
3)He may have had an unrelated reason not to want to involve authorities, for instance if he were high or carrying drugs.
4)He may have thought it would be impossible to actually find his attackers, and going to authorities would only give people on social media a reason to attack him which would inevitably lead to death threats and a smear on his name.
5) He may, due to adrenaline, not have felt his injuries or thought he needed medical care.
* Why would someone who heard his friend being attacked over the phone not call the police themselves?
For many of the same reasons listed above for starters.
* Why would that someone not come forward with the evidence at the start of the investigation, and maybe offer his phone records of that time period for perusal?
See my other posts on the phone records. As well as others on both sides of the issue who have given many reasons he may not want to share his phone or records.
* Why would Smollett wear a noose around their neck for 45 minutes?
This one is just strange, but it's just as strange if the story is real or fake, so it isn't particularly relevant.
* Why would Smollett not provide police with evidence that might lead to the capture of his assailants?
This seems to be a repeat. Are you referring to the phone again? That clearly would not help find the assailants.
Some red flags about feasibility:
* How does someone who is attacked by two guys end up with just a tiny scratch and an alleged broken rib?
We don't have access to his full medical charts, so you're sort of minimizing and extrapolating from our limited information. We don't actually know what injuries he may have sustained.
That said, the attack as you noted would have occurred in a brief window. We don't know anything about the comparative fitness of the assailants and Smollett, any sounds or events that may have cut an attack short, their possible intoxication.
It is not rare for a fight to end without broken bones.
* How does someone with a broken rib walk round the streets for half an hour?
Already answered by another poster who experienced a broken rib.
* How likely is it than an attack took place in the few minutes of time that Smollett was not visible to CCTV?
I'll admit I haven't been following the minutia of the timing, so I'm not sure if we have so definitively narrowed down the time frame. But if we have, that's as much a problem for any alternate theory. When did he aquire the rope the bleach/fluid and the injury? Or the scooter or whatever. If those events are not on tape with a narrow window that would be as much a weird coincidence as the attack not being on tape.
Or maybe we're all just overestimating how much street activity is actually taped.
* How likely is it that an attack by two vocal men in the streets of a big city was not seen or heard by a single independent third party?
Again something we're not sure of. Police don't make every possible witness public immediately. That said, it was very late on a bitterly cold night. Not hard to believe that a particular block would be deserted.