Don’t know or care about formalism here. But from a common point of view, that is just some pedantic bullshit (even if true at all) because when we say “dinosaur” we always mean animals from millions of years ago. Same level of annoyance as those crazies who claim that “water isn’t wet”.

Birds are dinosaurs like a lion is a cat. When we say “cat” wie also always mean a felis catus, but that doesn’t change the fact that a lion is still is a cat.

Same with birds and dinosaurs. It’s not pedantic to say that birds are dinosaurs, it’s pure, basic biology. And not even advanced biology. Everyone who made it past year 6 in school should know this. Lack of education is nothing to be proud of.