What's the correct procedure for dealing with this?
I have tried flagging it for moderators' attention as per this meta post, but the flag was promptly marked as invalid.
I have read the questions listed above as possible duplicates and have even linked to one of then. Answers to all three questions more or less recommend the same procedure, i.e. flag for moderator attention.
That was what I did. However, the flag was marked as invalid costing me flag weight points!
Don't get me wrong, I'm not bothered about the points. But the fact that I've been penalised for it implies that I've done something wrong hence the confusion (and this question).
Considering Jeff's comments below and the other related questions, I'm shall assume that the correct procedure is still to flag such questions for moderators' attention and the reason why my submission was marked invalid was simply because the question is potentially on-topic.
Whether the said question is on/off-topic is debatable, but that isn't really the focus of this question.
I shall yield to the wisdom of the mods and move on.