I don’t think anyone is saying it’s Ok because we did it. The yahoo’s on the ground that fired the missile screwed up - just like we did. But the airliner could have avoided the air space as well - just sayin ...
At least the Vincennes had the excuse that they believed they were shooting down a fighter jet fixing to launch an Exocet at them. The previous year, two Exocets fired by mistake from an Iraqi fighter (Saddam was an ally at the time) slammed into the USS Stark and killed 37 sailors. By contrast, the Ukrainian shoot was strictly offensive.
But the airliner could have avoided the air space as well - just sayin ...
As I recall, the USN offered the same defense in 1988.