Well, by definition a nudist is someone that prefers to go nude wherever possible. Nudist also generally back it up with that nudity isn't about sexuality and is a way of life for them. This was just bloom enjoying his vacation and has never said anything that he is a nudist.
Until someone says whether they are something or not, we can all assume he is or isn't, but that doesn't make it correct. He for sure isn't advocating for more nudist places or anything like that.
People also make such a huge deal when something like this happens. I mean, who really cares whether he is or isn't? He's a guy. Another human being. People always putting celebrities on pedastole's like they're gods to the rest of mankind.