That just them not knowing the difference. The current P99 frame style is still "gen 2". the SW99 was a clone made partially by Smith & Wesson for a short amount of time. The only real difference for holsters on the P99 is if you have a true Gen 1 with no pic rail. If you have one with a rail, their holster will work. If you have one without the pic rail, their holster will work with some time and a hair dryer.The only P99 they (Alien) support is the P99 Gen 2 (SW99). I Googled this weapon and it looks different than the gen 3 P99AS.
I ended up purchasing a LightTuck Kydex IWB from Vedder Holsters. I hope it's good.