I was with Lin before the Maria incident as well, but then all that happened. Someone he cares for got hurt, not necessarily physically, but emotionally and mentally. That can be worse than any physical torment one can endure. As far as we know, she could end up with PTSD from it given that sudden enslavement after being roughly handled during apprehension can be extremely traumatizing. This isn't just an isolated incident we're talking about, it has the potential to scar her for life and we have yet to get confirmation of whether or not it did. If you have someone who needs to be apprehended, perhaps a criminal at large, perhaps a slave on the loose, you don't just rough them up the second you have them in a corner with no way out, especially if they came into your facility willingly. We can't ever confirm it, but maybe they would not have resisted at all if they had been treated normally, but no, the freaking security bot had to use force as if she was trying to run away when she never even had a chance to try just from the suddenness of the apprehension. If they had explained the situation, she might have submitted with no need for security at all, and don't even get me started on if explaining it to her directly was an issue or not because she is part elf. There was a human right there within earshot and the staff could have talked to him while she was there, she would have heard every word.
It would have been my first action when I got back assuming she was already available, I would have checked every day until she was if not and then bought her when she was. It monetizes and incentivizes the enslavement of elves, but the only other way would be a raid that could ultimately have ended in her death from being caught in the inevitable and quite literal crossfire.
In her past is completely different than the Maria situation. With her, it wasn't a past event she just happened to bring up in conversation, it happened right there in front of him. Of course he's going to act the way he did, being an eyewitness to her terrible treatment even with no discernible resistance indicating the potential she might have simply submitted once informed and the complete lack of indication as to why this all was happening. They literally told them nothing, they just sprung the security bot on them with zero warning. They weren't even aware of her being half elf until after Maria was back out of state custody.