Again, not according to the law. This is my own layman's reading of the law, but as far as a I can tell, you can't claim self-defense if you attack someone because of a
verbal confrontation. The standard for self-defense is you have to be in fear of death or grievous bodily harm to you or others. Which is pretty much impossible in a verbal argument, unless you're dealing with Black Bolt or Black Canary.
Now McGlockton could have claimed self-defense in the likely assault case that would have followed if Drejka wouldn't have shot him, but I doubt that "I had to attack him because he was verbally giving my partner **** about illegally parking in a handicapped spot" would have met the reasonable person standard.
I think everyone can agree that Drejka was being a complete ****, but it was McGlockton that started the physical confrontation, which negates any claims of self-defense, SYG or otherwise.
I'm not a lawyer, so I could be wrong, but I don't know of any successful claims of self-defense where the person claiming self-defense
started the fight unless the other person was waving around a gun or knife or something. But just standing there arguing? I've never heard of it, but again I'm open to corrections.