Hmmmm... straw man, perhaps?
Yes. The people who were offering rebuttals to arguments I never made in the first place were erecting straw men.
I'm glad we can find such areas of agreement.
As you yourself seem to be affiliated to the building trade, you should be aware that it's unusual for the main exterior door to any premises to need a key to lock it shut (and therefore to unlock it again).
More than affiliated. I've been a full-time construction professional ... in the field ... at a number of different tradecrafts since the early '70s. I've worked as a general contractor field superintendent on heavy commercial and institutional construction since the late "80s.
As far as such lock configurations being unusual, you are mistaken. This is
exactly the way a "double deadbolt" lockset is
intended to work. Not only are they not uncommon, for many decades they were (and still are by the more sales oriented)
recommended for additional security on residential entry doors.
The thing is, in residential applications they are intended to work
in conjunction with and not in the absence of a
functioning spring latch.
In most residential applications (in the U.S.) this involves two separate locksets, but the functions can be and sometimes are incorporated into the same device.
I would hope that you can see that this presents a potential safety hazard, if the occupants of a house are unable to find a key to unlock the door in the event of (e.g.) a fire inside the house.
You are quite correct about this, which is why fire safety professionals have been at odds with home security people concerning exactly this issue for many, many years. This has not impacted the sale of double deadbolt locksets for residential entry doors much, though, as any visit to a home improvement or building supply store will show you.
A number of precautions are recommended by fire safety pros when such a lockset is used, including ensuring that a key is always kept near the door. (I suspect that the implications of this do not escape you.) Variations on double-deadbolt locksets (including ones which use a removable thumbturn on the inside instead of a key cylinder, but allow the removal of that thumbturn only with a key in the exterior cylinder, providing the same security while requiring a conscious decision ... and a key ... on the
outside of the door 
) are available, and gradually replacing the double deadbolt.
But the double deadbolt isn't dead yet, and many, many of them will remain installed for quite some time to come. Things like that change slowly in buildings. Think how many doors still have skeleton key locks.
Indeed, I believe that buliding regulations in many parts of the world stipulate that for new installations the main exterior door should be able to be unlocked from the inside without needing any sort of key - I'm sure you'll correct me if I'm wrong in this.
Phrased in the fashion you chose I am unable to correct you, since I don't know the building codes in "many parts of the world". Perhaps you are more conversant with them than I am.
In the U.S. there is a patchwork of building codes, since this is usually addressed at a state, county, and/or municipal level, with a bewildering number of variations. The National Fire Protection Association (which is not a government agency) provides guidelines which the various jurisdictions may choose to incorporate if they so desire. Usually they do, or at least some portions of the NFPA code. Not always, though, and not necessarily all of it.
In general, door hardware is addressed based on occupancy and use definitions (as is everything else, for that matter), and residential use spaces are not subject to requirements as stringent as those suggested for public and institutional spaces.
This doesn't even address the issue of owner or resident modifications after code compliance for new construction is verified. Quite frequently such mods are not even addressed by the building codes themselves, and slip through the regulatory cracks, as it were.
In short, as far as the parts of the world I
do know about are concerned, you would be wrong about this more often than not. Nearly always.
And this door - whether by accident or design - was indeed unconventional in this respect.
It was unconventional in the sense that, because the spring latch had been intentionally disabled, it was no longer possible to secure the door closed in any fashion (using the door hardware) without a key.
I agree that this is not a common condition in residential entry doors.
However, in the sense you seem to be intending, that it is unconventional for a residential entry door to be fitted with a lockset which requires key operation from the interior side
at all, you are quite mistaken. It isn't even particularly unusual.
We're not talking about the need for a key to open the door from the outside, by the way (and as per your straw man above).
What straw man would that be? That the balcony door was also a potential means of egress from the apartment?
We're talking about the fact that the door needed to be locked and unlocked from the inside using a key.
Which I have never contested.
This was the case on the night of the murder, so it's entirely correct to say that on the night of the murder, Guede (or anyone else) was faced with an unconventional situation where a key was needed to unlock and open the main exterior door.
Aside from your mistaken insistence on the term "unconventional", this of course is based on the premise that Guede (or anyone else), for whatever reason, found himself in the apartment with the entry door locked in the first place. There is something slightly circular about that, but I wasn't addressing that question in the first place.
You've already agreed that the balcony door offered an alternative exit, which is all I ever mentioned.
That's two things we agree on.
Is there some peculiarly British meaning of "straw man" which I am unfamiliar with, or are you just tossing the term around because you think it sounds erudite?
