I believe Ross has mentioned that he likes the 40k, but isn't really a fan of the Dark Heresy system, though I could be misremembering things.
Also, what the upload schedule now? Duality, Masks, then One Shot? Or is Dungeon World tossed in there somewhere too?
Putting words in Ross' mouth: It's a complex system which he would need to teach to all of the other players for probably only a game or two and they aren't big fans of Warhammer. So, more effort than it's worth basically.
Yeah, that's it. I am the only one who has any interest in 40k - I have DH, RT, and BC but learning a new system takes a lot of effort and time, especially when there's no stated interest from the rest of the group. I'm currently prepping for 13th age since many of the other players have expressed in it. I'll run Shadows of Eldolon sometime in January.
Posting schedule is Masks, Duality, one shot. There's 1 more DW game in the can, but that's it. I also have some more 5E from Bill, Sean, and Anne, Call of Cthulhu (booted and suited from The Unspeakable Oath), and Our Last Best Hope, among others.