I guess ... although it's an imperfect solution.

PMing people with a filter email address might work, but it depends upon their responding to it for it to have any significant impact ... and I'm not really sure how well it would substitute for a 'blog' kind of OLP; it'd be fine for a mailing list without any personal communication because I can't trust others' email service providers not to scan the content ... or for personal communication, but then I'd have to rely upon people to give enough of a shit about the contact to remember they had a separate email account for that purpose that met the requirements for privacy/security — and most won't, trust me (even though it's installed on their phone, I can't even rely upon some of my friends to make use of Signal and have given up messaging them in the interim, because they never reply).

Besides which, I'm increasingly less enamoured of Medium as a platform ... meaning I'm not altogether convinced I'd even want to open another account ... and there are no alternatives I can find that make any sense from the point of view of either privacy/security, economics or reach.

So, I dunno ... I'll give it some thought, maybe set up an email account just in case - watch this space.