Ok George, let’s say you’re right and that after any mid-air collision, the aircraft might break up in mid-air, or pieces could fall off, even if the collision seemed to involve no more than a small dent. I hope that’s a fair summary of your position, without any strawmanning, ad hominem, etc.
But we can’t just draw the line at a mid-air, can we? What about a birdstrike (or suspected birdstrike)? We’re just talking small dents, after all. Sure, the spar mightn’t fail, but maybe pieces will fall off. It might’ve been a big, heavy bird - we’re not really sure.
Or what about severe turbulence? Perhaps it’s overstressed the airframe. Pieces might fall off, or the entire structure could fail. We really don’t know.
So there you are, George, in your 200t airliner planning an approach to 16R in Sydney. But you’ve just had a suspected birdstrike or flown through some nasty turbulence (you choose). By your own reckoning, you simply can’t guarantee that pieces won’t fall off or the structure won’t fail. Are you, the scientist-engineer-pilot, going to continue your approach over a highly-populated area in a 15 kt headwind to the longest runway in the country, or are you off elsewhere? By your own logic, I don’t see that you have any option but to divert, after your suspected birdstrike/spot of nasty turbulence.
Let’s take another example. Can you absolutely guarantee that the aircraft you’re about to fly has never had another pilot overspeed it/overstress it/do a hard landing, without reporting it? Unless you’re the only one who’s ever flown it or it’s straight out of an inspection, I don’t think you can. In which case, you simply can’t be sure of its structural integrity, and you shouldn’t be flying it over a built-up area. In fact you probably shouldn’t be flying it at all. It gets a bit tricky, doesn’t it?
This doesn’t prove anything, but might be of interest:
I’ve known quite a few people who’ve been in mid-air collisions; witnessed one from the ground; and known of numerous others. In each case all the structural damage and separation of parts happened at the time of impact, not subsequently.
I’ve also known two pilots who died when their airframes failed without warning in flight, in separate incidents. They hadn’t overstressed or oversped, nor collided with anything. So you can never really be sure, can you?