To me, infantalise looks right whereas infantilise doesn't. Maybe I'm thinking of infantacide... I was going to make a joke and say I should know the word infanta as I did my doctorate on the politics of the court of the Infanta Isabella of Spain but I didn't think anyone would believe me. So I didn't.

I don't remember the Nell Howell discussion, I wonder, do you think it might have been on Pros Lit? They had some really good discussions way back.