I agree with banning potions but at the moment playertime isn't working, so a good fix is to use the night vision one, is it possible to leave that one in for the timebeing?
Easy fix, just ban splash potions, but drinkable ones are fine. You can't hit other people, and you can use them on yourself.
Yeah, I feel that banning splash potions is the more reasonable course of action. There's only a few of them that are of any use in creative, anyway.