What happens if the AT Protocol will get large adoption? Will it be a good or a bad thing? Will it lead to more fragmentation? Will it be compatible with ActivityPub?

I stumbled upon this, but I don't know how it would affect the fediverse. The integrated account migration / moving sounds interesting, but on the other hand, it seems to belong to a company rather than a standardization comitee (W3C ActivityPub). I think it should be prevented that there will be a ActivityPub and AT fediverse that are completely isolated from each other (fragmentation)