Jon Pretty sounds like a complete creep and yes, based on this account, a predator. That being said, there is a court and criminal justice system for a reason. While I empathize with the author, and utterly despise the archetype of high-status men who use their status within programming communities as a tool to target women, I find the nature of these kinds of posts to be counterproductive. Therapeutic to the author?…
Most people let bullies get away with it because even stepping in as a third party means standing up to a bully. It can be scary, but even if there's no real risk it's still a fucking pain in the ass. Who wants to get into a mud slinging competition with a predator? Or get a harassment lawsuit? If someone is willing to harass other people this way, they will certainly harass you this way.