Helldivers 2's popularity increased when Arrowhead Game Studios asked players to not play the game because the servers couldn't handle it.
It could just be the divers getting the heebie-jeebies, but it looks like Arrowhead could be teasing the squids doing a thing.
As for why it's such an obvious pick, well, Helldivers 2 and 40k occupy a lot of the same 'satire of intergalactic fascism' ...