I wasn't being a dick but I will now. The 20T "heavy" TP rule is designed to advantage ex Military people with P3 (Electra) or C130 time. The fact that the Q400 qualifies by about 200kg is a coincidence. It should read "heavier" than 20T but HR write the ads not flight ops.
I've also seen "Frozen ATPL" on a few ads in Oz as well. Going call me out on them?