Oh definitely, I think that any form of infantilism, sexual or not, intentional or not, would arouse him. (Maybe he likes kids too much lmao)

A scenario that would happen would be something like: Yuuji and Nobara begging their sensei to go to McDo after a training mission and they would say things like:

“oh Sensei, my tum-tum is empty, we need some nuggies”

“Yes Sensei, we want to eat some chicky, pretty please”

All that in an infantile tone, messing around. Of course, Gojo would fall for it. Accepting their request with a small blush, trying to hide the big bulge that just appeared in his pants.