Lol guys, stop analysing this so much :D It's an anime, just take everything at face value. It's a cute girl who might join the party. You also only have 12 episodes to build your harem. Gotta forgive!
For the record though, my two cents:
You've been partying and adventuring with this girl for ages. You literally risk death every day with her. I think that's enough for anyone to become a friend. She does some bad stuff to you, but it's clear she has reasons and frankly, she's pretty fuckin' pitiful. Then suddenly along comes this very mean looking man who you've already fallen out with before, who's being nasty to this friend that you're pitying and feeling defensive about. You have to remember that this MC is still only human, and I know in that situation I'd be forgiving the friend and despising the man. And does this man need motives? He's in a position of power over these much weaker children. You don't need motives to abuse that. It's pretty clear that abusing that means he gets more money because it's exactly what I'd do in that situation. Power can always become money.
Also, just some fun biology here: The 2 X chromosomes argument is kinda shitty imo, cos you can actually be a woman (biologically, ignoring mentally) even though you have XY. In some cases, the Y chromosome fails to activate, testosterone glands don't develop and the body and mind is female in every way, except genetically. Now, these people don't go through puberty on their own, so I suppose they're not 100% women... they can have oestrogen and other female puberty-related hormones injected though, which will trigger puberty. This does show though that these XY women are considered women in the eyes of science, and "the eyes of science" is pretty much law when it comes to stuff like that.