I request guidance on what to do if a user repeatedly reposts deleted content in self-moderated threads—especially if the user reacts to self-mod deletions at a speed which raises reasonable suspicions that the user deployed a spambot to defeat self-mod. [...]
AFAIK you should publicly (in such a way that both a moderator can verify and the user in-question is sure to notice) warn the user to stop posting in your self-moderated thread (e.g. making a dedicated post in your self-moderated thread as well as editing in said warning into the OP). If the user doesn't heed the warning, you should report his post(s) and the user will be (temp)banned.
Thanks for the response, mprep. I think that reasonably preserves the DIY ethos of the self-mod feature, whilst preventing net-abuse tactics from being deployed against people who don’t actually have administrative tools to respond to that. I will be guided accordingly.