It's a comic book, dood. The fact that a character can even destroy an infinite amount of universes at all makes no sense, as it implies that the total amount of universes in the multiverse had a quantifiable end--which infinity obviously does not. Again, how much sense does it make that AM was able to destroy all but 5 of infinity? Answer: it makes no sense, as infinity cannot be fractionated--but AM did it nonetheless.
Stop trying to project logic into the illogical. It's called 'fiction' for a reason. 👆