AITA for putting the kibosh on Sons' naked vacation?

I have boys 18 and 19, who will be completing their freshman and sophomore college years in the spring. They are doing great in school, excellent grades despite both being on athletic teams and extra curriculars that are a time suck. I'm very proud Dad for how they are doing.

As a reward for doing so well I have told them I'd pay their way for a vacation during their spring break in a few months, anywhere that they'd like to go (well, within reason. If either picked Antarctica we'd have to talk about that).

The boys wanted to go to an all-inclusive resort in Jamaica, apparently a whole bunch of their friends from school have the same idea and want a big fun group trip.

I was all for that, and all for Jamaica. That sounds like fun (I've been to Jamaica years ago and had a great time). However a combination of overhearing some details and seeing some info has me a bit unsettled.

They have plans to go to a resort called -- get this -- Hedonism. I looked it up (maybe that was my mistake). Hedonism is apparently pretty raunchy, very "adult," and is pretty much the Caribbean's answer to Hefner's Playboy Mansion. It's got just about everything you'd want in a resort as far as activities and such, but just about the whole place is "clothing optional" and some of the places like one of the beaches and a couple of the pools are actually REQUIRED nude. And they have things like "playrooms" and "happening huts" and one can only imagine what goes on there. There's theme nights like "naughty nurses" and "fetish leather and lingerie."

I gave that the hard "nope." I want to reward them, but I'm not about to fund what sound like nothing short of an orgy. They were NOT impressed with my decision, not in the least.

So am I an asshole for backing out of funding the vacation I promised?

P.S. I am not a prude. Far from it. I know they have sex. They are gorgeous popular athletic boys on a college campus, I'm not that dumb. They're probably having a lot of it. I'm fine with that, encouraging even. I bought them both condoms starting when they were 16. I want them to have fun, I want them to get busy as long as they are smart and safe and respectful, and make great college memories. I just don't want to pay for a nude-a-rama at the Caribbean fuck-a-torium on my dime.

EDIT for formatting