It's a WAitW if it's misleading. The post describes a (pattern-matching) heuristic for when to unpack/taboo categories used in an argument, specifically those categories that contain the idea under discussion as a non-typical instance. Before you unpack a category, the heuristic only indicates what to unpack. After you unpack, you'll be able to judge whether the argument stands or essentially relied on the category not getting unpacked, in which case it's an instance of WAitW.

As Konkvistador notes, people may misuse this argument by crying "WAitW!" without doing the unpacking. But this is a standard problem with many ideas about ways in which people err, giving clever arguers new ammunition, and perhaps this bears repeating more frequently. It is not a problem specific to the post, it doesn't detract from the idea itself, correctly understood.