Ok I'm actually down with "All Space Marines are men" if it's in the context of "All Space Marines are men, regardless of assigned gender at birth, we don't care what you thought you were, if your genetics match the gene-seed for the chapter, we're pumping you full of splices and hormones and you get to be a huge jacked war-dude now."
Like, if they are picked out as kids and made into space marines before their natural adolescence, then basically ALL Space Marines are a kind of transmasc post-humans.
Forced transition into a tool of war is horrific and honestly matches the ridiculous grimdark the setting claims to portray/parody. That plus women in the Astra Militarum makes me potentially actually interested in the setting again. #40k #SpaceMarine