I don’t see the problem with the late flag and confirmation or otherwise by VAR. A player being offside doesn’t suddenly, make the game much more dangerous and isn’t going to make an injury any more likely than any normal stage of play.
My point is more around if you lose VAR which I would support, as its added nothing to the game, then this incident may well not have happened.
The linesman has done the right thing, implementing the current rules, but football without VAR is so much better.