I was mostly looking for specific interactions to dig in to, but if you have a link or two for me to take a peek, we'll both know if it's worth it soon enough. You don't have to dig deep straight away.
There's no such policy , but it's abused as a way to censor criticism over behavior, which itself is a policy (RUCD)
There were a couple instances where user conduct concerns were raised on their talk page (in accordance with RUCD), and that user used USERTALKSTOP to censor the concerns. The outcome is that me and the other users who were raising concerns received a temporary ban (one permanent), instead of the concerns themselves being attended to and addressed.
Worse than the ban was the hours and hours of inane dialog on admin pages, defending your edit history, account history, intentions, etc. And the UI is clumsier and noisier than the worst 1990s web BBs
You can see how a seemingly benign non-policy can be abused to censor even well-intended volunteers.