I got this when I wanted to vote for a question to remain closed:
I picked the last option (intending to pick the generic off-topic reason), since I feel like the question ought to remain closed, although for a different reason than what it was closed in the first place. If this vote reason cannot be selected, why is it displayed at all?
Posting this here, as I suspect this is a bug in the software, not exclusive to the Retrocomputing site (though I have no way to reproduce it anywhere else). The feature seems to work fine on Stack Overflow, though; I suspect this is the only site where it was tested.