Depends how reliable a signal of threat it is, and also on how we feel about sexual status markers. As others have noted, the behavior that gets labeled "creepy" covers a pretty wide spectrum -- sometimes it's a reliable indication that the person you're dealing with is sexually threatening, sometimes it's an indication of inexperience or low status but not a strong marker of threat, and occasionally it shows up due to conflicting social protocols even when both parties are high-status and nonthreatening.
The latter's straightforwardly something to overcome, or at least to recognize and route around. The former's straightforwardly adaptive. It's the "indicator of low status" category that gets ambiguous, but I don't think it's obvious that we'd be better off if our concept of sexual status was weakened or abolished.
On the other hand, if something in our culture (rather than our basic emotional machinery) is causing us to unnecessarily conflate low status with actual threat, then that also seems suboptimal; even if the subject would be rejected either way, it can't be pleasant for either party for him to be assumed dangerous. In that case the fault's in the culture, though, not in the emotional reaction.
One of the lessons highlighted in the thread "Less Wrong NYC: Case Study of a Successful Rationalist Chapter" is Gender ratio matters.
There have recently been a number of articles addressing one social skills issue that might be affecting this, from the perspective of a geeky/sciencefiction community with similar attributes to LessWrong, and I want to link to these, not just so the people potentially causing problems get to read them, but also so everyone else knows the resource is there and has a name for the problem, which may facilitate wider discussion and make it easier for others to know when to point towards the resources those who would benefit by them.
However before I do, in the light of RedRobot's comment in the "Of Gender and Rationality" thread, I'd like to echo a sentiment from one of the articles, that people exhibiting this behaviour may be of any gender and may victimise upon any gender. And so, while it may be correlated with a particular gender, it is the behaviour that should be focused upon, and turning this thread into bashing of one gender (or defensiveness against perceived bashing) would be unhelpful.
Ok, disclaimers out of the way, here are the links:
Some of those raise deeper issues about rape culture and audience as enabler, but the TLDR summary is:
EDITED TO ADD:
Despite the way some of the links are framed as being addressed to creepers, this post is aimed at least as much at the community as a whole, intended to trigger a discussion on how the community should best go about handling such a problem once identified, with the TLDR being "set of restraints to place on someone who is burning the commons", rather that a complete description that guarantees that anyone who doesn't meet it isn't creepy. (Thank you to jsteinhardt for clearly verbalising the misinterpretation - for discussion see his reply to this post)