tl;dr: After about an hour, someone swung by and started editing and answering and whatnot, as one does. Pretty immediately after that, Bill the Lizard summarily insta-deleted the whole thing, no reason given.
I only saw this just now, about four hours after posting, having had other matters to attend to and previously having experienced that one often doesn't get much by then anyway.
Can someone shed some light on why my question was banished by the fist of an angry god?
Further info for us sub-10K plebs: it was a question about very puzzling SQL Server query behavior and how to iron it out.