The profile of the keyboard has little to do with it, because it's simply not visible in the photos on the auction site, although you could argue that I dug up extra photos and simply neglected to present the relevant evidence (which isn't the case: I was going solely by the photos from the page linked, and didn't investigate the profile until later).
The Model M is a very distinctive design due to its curved backplate and how this curvature is reflected on the area of the case that surrounds the keys, and very few keyboards could be mistaken for one. Even the ridge you mention is a direct consequence of this, instead of the imitation found in other brands. AQ6-COMPA is one of the very few keyboards that at first glance could be easily mistaken for a custom branded Model M (until you notice the keycaps are wrong). Mitsumi KPQ-E99YC is another. The Key Tronic keyboards will still trick you for a moment, but the narrow sides are a dead giveaway.
NMB RT-101/RT-8nnn and Cherry G80-1000 are both entirely flat on top and there's no way that you could mistake one for a Model M even for a tiny fraction of a second. They're inspired by the M, but no attempt was made to copy the characteristic aesthetics. My Monterey K102 has that wedge profile too, but it again it's entirely flat on top.
Even if you ignore all of this, it's still not a normal NMB keyboard shape. I think it's safe to assume that I've seen a few NMB keyboards, so your interpretation of my statement as indicating that I haven't the faintest idea what any later NMB keyboards look like is an illogical assumption. On the basis that I'm singling it out as a unusual design, then it stands to reason that it must look more like a Model M than any normal NMB keyboard does, which is the case.
