I see the OP in the cited example hasn't revisited ELL (or ELU, from where the question was originally migrated) for well over 2 years. Taking that into account, I suggest something along the lines of...
If it's more than a month or two (or whatever we can reach a consensus on) old, and the OP has shown no active interest in the question (and perhaps the whole site itself) the two primary options should be:
1: Vote to delete the question - if nobody wants to answer, what good is it?
2: Edit the question - if it was somehow "badly posed", but is nevertheless "salvageable".
As the meta OP here points out, not all users will have sufficient rep to be able to do either of those. But it only takes 15 rep points to be able to flag for moderator attention, and personally I don't see anything wrong with new(ish) users being able to suggest that a mod might consider taking the action on behalf of those unable to do so themselves.
Obviously that's not ideal, and it would be better if higher-rep users such as myself took responsibility for these matters without having to involve moderators. So if I were a mod myself, I'd probably only take action if at least 2-3 lower-rep users were calling for it on any given question.