...can anybody come up with a good suggestion on how members can best protect people who are unfortunately getting abused through no fault of their own

Perhaps a PM of support explaining why you're not launching in to the abuser on an open thread. That would greatly reduce the temptation for them to get sucked in. And it reduces the temptation to get sucked in yourself, which is probably a greater temptation for many people.

People don't actually need protecting so much as solidarity. And as for people who make a habit of abusing others, a boycott is probabaly more effective than a ban, and it doesn't need anyone's permission or approval.