Maybe next time someone has a "chat" with the guy, it would be worth mentioning that many women have reported having trouble with him and that if he doesn't stop being annoying he's going to be reported to the authorities?

Can't help fantasize imagining the "conversation":
"Nice weather hey?
- Do you know that there's a lot of women in town who are really tired of having you suck their wheel?
- Uh..?
- If you don't leave me alone right now I'll have to report your behaviour."
[Creepy Bearded Man rides away.]

Obviously I'd make sure I strike conversation in a populated area.

And I would be tempted to drop an email to the trail authorities, if I was in Seattle...