I know its not comparable, but for the sake of argument, let's try.
You know you're injured, and your employer knows that as well. You then go and "work" for somebody else, pro bono by the way, you actually don't "work" at all, because the guy that wanted you there doesn't even need you and then, you come back to your employer and say, "i'm gonna go on a holliday for a while, and when i come back, i'm gonna go on a surgery and won't come back for a couple of months, that's ok, right?"
Tldr, just saying, could have been done with more consideration to United, but ok.
Maybe its just me.