I just take a paper towel myself. If there is a guy standing there holding the only paper towels in the bathroom, I'll just ask him why he's holding them. I wouldn't use one from him either, that just seems gross. I wouldn't tip for it in any case. It's just slightly glorified panhandling, I assume it isn't at all condoned by the club owner and they'd probably throw the guy out if they were aware. I haven't actually seen it in the US, though, just at international airports outside the country, so maybe the dynamic is different here.

Most people prefer to play along and have a good time and not think much about it and focus on the night itself. Less about making a point and more about having fun at the place you'll walk back into once you exit the toilet.