(This is my speculation) but I think the cat didn’t really actually made them into omegaverse, but instead have them experienced Cat estrus or cat heat, since that is what the cat think is similar to the whole omegeverse spiel mc tried to explain to the cat deity, also, in one of the panel the Cat said they can’t really do a world wide scale wish like changing the whole universe into a/b/o, since that would be complicated
That's a great theory in general, but doesn't explain why ONLY HE has cat ears. The omega doesn't.
https://www.mangago.zone/read-manga/pendulum_kemonohito_omegaverse/
There is an omegaverse tendency were omegas are human and alphas are furry.
The opposite with human seme an nekomimi uke is also possible.
It's not this case but it could be because of the specific manga the uke was reading
Whyyy does ge have cat ears. How tf is that related to being an alpha.