Both Cavill's supposed love of the books and sexism seem to be exaggerations of the same grains of truth. For example, the female showrunner the show did say Cavill often had lore points to add in and little things to suggest, but that Cavill was extremely polite and never pushy about them (she was specific). Different groups exaggerated different parts of these truths, to try and make Cavill into either a sort of Incel-Hero figure, fighting the brave fight of being a misogynist ultra-nerd, or Cavill into a sort of Incel-Villain who hates women and obsessively attempted to push lore. And this whole "Oh he quite because he is a PURE TRUE NERD and couldn't stand what they are doing!" seems like pure fantasy to me. I'm pretty sure he quit because they cast him in a new Superman movie (which then fell through).
Somehow I don't think a dude who looks like that and has the GFs he does is really on the side of the incels nor is a guy who did three series of The Witcher going to quit for the fourth just because of "lore problems".
Height and "muscle" have nothing to do with each other, and it's kind of weird to suggest they do. My point is that there are a lot of actresses over 5'9" and they universally have more trouble finding roles than shorter ones, so it's sad to see a role specifically for a tall character, who frequently noted as being taller than other characters, be given to a relative short actress. I'm assuming you haven't read the books given the "strength" comment - Nina Zenik is fairly strong (she is a Heartrender) but not shockingly so. Also distinguishing her personality from her magic is kind of a major plot point in the books (and whether they're separate or interrelate or what) so I won't go into that further without spoilers lol.
(NB I am biased, my wife is just over 6' and it's sadly rare to see any representation in her height range on TV - Netflix did actually do a "tall girl" teen drama movie - literally called Tall Girl - which she really related to. And the actress in that was all of 6'1")