My Dad hooked me up with playboys when I was... well, younger
I'm glad he did too, I was literally about to bust.....
I have two younger boys now. We gave most of our adult swag to friends and the rest to charity. A freeones towel, would be something we would have kept, it's not naughty enough to toss.
I would have no issues with my Sons taking the towel at any age. It's no different than a Marlboro towel or a Corona towel. Or a damn blanket for that matter...