Fairly recent changes to StackExchange have encouraged users with sufficient rep (and close votes remaining) to vote-to-close rather than merely flag for moderator attention.
I think I understand and agree with this approach, and after a bit of muddling with trying to salvage this question, cast (so far the only) vote to close.
However part of the salvage for off-topic but otherwise good questions can be trying to get the question migrated. I realize there is an open ticket to provide more options for recommending other forums to migrate questions to, and that there's a decision that needs to be made at the target forum whether to accept a migration.
In the present case there was a comedy of errors as I mentioned a couple of alternative forums in a comment on the question, then wound up pointing (without realizing) to an earlier question on much the same topic that the same user had posted (SO). The user then posted a duplicate question on the other (beta) forum I'd suggested, only to have that swiftly closed by a moderator on account of the cross-posting.
With the benefit of hindsight I'm wondering if a comment recommending "self-migration" is a bad idea, even if offered in the spirit of salvaging a question. I'd appreciate a better picture of how successful migrations are accomplished.