I had to deal with an eerily similar situation several years ago, where a user said her abusive ex had tracked her down on the website I helped moderate. I understand where you’re coming from because she specifically told us not to ban him (she feared potential repercussions).
As for the topic at large, I’ve asked about it before and stand by my request for a true, two-way block. It’s all well and good to tell people not to click the “view hidden content” links, but…have you observed human nature lately? The concept of self-control has become downright quaint 
And in other situations, seeing the “view hidden content” link itself could be an upsetting reminder of an abusive exchange or otherwise unpleasant experience. Again, all well and good to say people shouldn’t feel that way but they do, and that costs our site valuable members (and no, these situations aren’t black-and-white violations of our rules, either - there are multiple nuances where we can’t just ban people and call it a day).
If the blocker and blockee’s account could mutually cease to exist (as on Facebook), it would save so much time and trouble. Our users request this feature on a repeat basis, and each time I have to tell them Discourse doesn’t support it. Quite demoralizing.
Is this a thing yet? I’m not in a position to mess with any CSS for the site, but if this were part of the forum admin UX, we could do it.