I think the reason the sharing information stood out to me is it's the one thing she fully controls. His abuse of her employees is really terrible, but the only thing she can realistically do about it is cut him off - and she should, but if he's bankrolling everything and offending him means losing it all, it can be really tough to make the call, especially if she feels like he's giving her an ability to help other people that she wouldn't have otherwise. At some point it feels a trolley problem: do you swerve the oncoming train away from your employees at the price of all the people you are helping?

The sharing confidential information, though, is 100% up to her. She could just stop volunteering that. Which makes me suspect that she really isn't as opposed to his overall behavior as the letter makes out and is probably just also terrible.