They wouldn't have done that even if they were on some really good weed. Quoth my local blackshirt, "they're not going to tear down a huge chunk of existing background, especially when it involves Space Marines, when there's been so much time spent updating the background to be more consistent with Black Library".
Asking a blueshirt and the local gamers around the painting table today revealed that it was all bunkum anyway.
Re. Squats, they've been alluded to in Codex: Orks as well (though that one's often overlooked for some reason), and the novel Gunheads (which gets extra bonus points firstly for being written by Steve Parker*, and secondly for being set on Golgotha) has quite a long sequence in which the Imperial army has to cut through what can only be an ancient Squat stronghold -- notably, the Adeptus Mechanicus delegation ends up going walkies, which leads to the architecture being described in quite some detail.
About the book itself -- the Special Rules section strikes me as something that might fit nicely into a 40KRP core rulebook, as the layout feels so similar to how weapon qualities, Skills, Talents, and Traits are laid out.
*The fact that Parker isn't one of the most well-known Black Library figures probably leads to Gunheads being overlooked, but I like his writing style. It's descriptive enough without being too showy-offy.
