Many work places try to exert control over the lives of their workers in ways that overstep the employer/worker relationship, often in an attempt to avoid litigation and bad publicity. Mine does much the same, not that anyone listens to them because the HR girls are a merry bunch of morons. Like there's a snowball's chance in Hell I'm going to trust them with my own safety when they have trouble filing paper work properly. They only work day shift anyway. Night shift is anarchy, which is the way we like it. But they don't feed us on night shift, which kinda sucks.

I digress. Look, if there's no evidence that a fellow coworker is being anything more than a bit creepy and awkward - standing outside for too long, putting on sunglasses, being socially inept when trying to chat - then I'm going to argue that handling the situation diplomatically by oneself is far safer for both parties than going to HR, especially if the guy has the potential to be dangerous. HR can't do anything if there's no real evidence of danger, and sicking corporate authority figures on him is far more likely to provoke anger or resentment than if this coworker had just talked to him herself. Also remember that HR works for the company, not you or your safety, and they're going to do what's in the company's best interest, not yours. This applies to both parties. If you ever need to go to HR over something which may become a legal dispute, record everything. Don't trust them to record it or to represent it accurately in Court.

Now, maybe he's omitting some things and this coworker had good reason to think he was stalking her. If so, then my apologies to her and the HR girls. But I can only go by the details given.