Help with community harassing homeless family member.

Hey everyone. I could use some advice. For anyone reading I'm in Ontario. My brother in law was a homeless addict for the past two years. He's just started to get clean, and get his life together the past few months. He's been known to hang around some trouble makers, but never partakes in their illegal activities (ie; stealing, robbing etc). Due to his close proximity with these people from living in the local shelter, he is now being harassed by the towns Karen's (as I've been calling them). They've created a Facebook group dedicated to "keeping the community safe". My problem is, it's anything but that. They've been ignoring all the actual culprits and fixating solely ony brother in law. Because he's not doing anything wrong, he doesn't feel the need to hide. They've been posting pictures, videos, and his current whereabouts on the page for months. I was on there. Standing up for him, and the shelter they were blaming for all the incidents in the neighborhood, but when I put my foot down and told them In no uncertain terms to knock it off when it came to my brother in law, I got banned and blocked and they threatened to call the police on me for harassment of all things. The problem is now, I have people keeping me informed of their postings, and they're still at it. They're essentially stalking him at this point, when he's doing nothing wrong. It's been getting to the point that he can't go anywhere around town without being harassed or threatened by someone who's seen videos or pictures of him online, assuming he's the local thief. And they even (unknowingly) outed his new place, where he's living. He drives around on a modified tractor, and it drives them nuts. He and his worker at the shelter have talked to the police numerous times, and they say there's no problem with the tractor, but these women keep posting and harassing him.
Anyone who's known someone who's dealt with mental health and addiction issues knows this is the last thing he needs right now. But he refuses to call the police. He hasn't had the best interactions with them this far, so he prefers to avoid them. I guess my question is, is there anything I can legally do for him, or on his behalf to get these women to back off? Isn't what they're doing technically harassment? I have plenty of idea on what I could do, but none of them are productive, more of an eye for an eye. Any insight or advice would be greatly appreciated.