It's a knotty problem, pun intended.

Park operators absolutely should be talking to guests about attire that might be unsafe or, yes, trigger a wardrobe malfunction. Just like they would ask me to tie my glasses to my head or take them off (which is a problem if I went to more extreme theme parks...I have heard of people getting to the front of the line only to be told glasses are not allowed at all, and it wouldn't be any fun to ride a roller coaster without being able to see more than a blur).