Her manager probably did her a huge favor

Yeah, navigating disability leave can be a little rough

Not as rough as being PIPed out though, which was probably the other most likely path in front of your friend

Nope! Her manager had no concerns about her performance and has expressed regret about the situation because it has made everyone's life harder. The manager likes her and wants her to stay at the company, but because she's a "problem" for HR they want to fire her.