But if the US becomes the country that writes the world's aviation regulation,
It already is, and always has been.
The bulk of EASA regs are FARs, copied/pasted, usually (not always) with the paragraphs renumbered
it can and will abuse that position to the competitive advantage of US industry. Not because it's evil, but because it can, and it's not stupid. It's the role of a government.
Yet there is no evidence of the USA ever trying to cripple European plane makers by writing the FARs to suit its own makers.
It is
EASA that has done that, by blatently defining "complex" to be (IIRC) > 18 seats, or ME turboprop, or jet, which lets in the TBM and the PC12, while sticking a finger up to Beech's King Air. If Europe had a light jet industry, EASA would not have done that, for sure. Diamond's SE jet has been stillborn for years... not a shock given its MTOW being > 2T and its certified ceiling of FL250
The FARs have been pretty much fixed for donkeys years, with the meaningless 12500lb (5700kg) limit for a Type Rating, etc. The USA doesn't change things for the sake of it. If it works, they usually leave it.
The rest of the world, including the darkest Africa, runs its own CAAs, and if you didn't like the FAA, and there was no EASA, and Europe's CAAs contracted certification to the FAA, you could always reg your plane in the People's Democratic Republic of Upper Volta, etc.
But the fact is that Europe has always had its own certification regime so how exactly could the USA change its FARs to suit US business? You can fly a Euro-reg plane worldwide, if you have matching pilot licenses, and that includes keeping it on US soil. The reason why almost nobody keeps Euro-reg planes on US soil is because they would fail their next medical (lack of a brain).
If the USA was to ban Airbus selling in the USA, or selling to the US military, it would be due to bribery of US officials by Airbus.
This discussion is worse than the similarly contrived argument for Galileo.
So "Europe is collapsing like a pack of cards" because the banks were overregulated?
The EU is collapsing because career-focussed Euro politicians who could not see past the end of their noses created the Eurozone, invited the southern countries to join it even though everybody knew it would wipe out the little export business they had, and the southern countries did the obvious thing which was to borrow billions at ~1%, which they could do because everybody "knew" that Germany would always pay it off (and anyway the bankers got their bonuses early so a later default wouldn't matter) and they had a huge
mexican party with it
... oh and bought a few tens of thousands of German cars while they were at it. Germany paid
massive bribes to lubricate business down there, too, which probably didn't help. Come to think of it, they did the same in the USA too.