Bolded is the problem though. I support Hillary, and have already voted for her, but this is a really shitty thing to do.
Regardless of how well prepared Hillary is, this is extremely unprofessional and doesn't look good. Saying "Well she was likely going to be prepared for that question anyways" is a deflecting from the fact that one of the debate questions got leaked and that is really shady. You can be a Hillary supporter and still say this is an extremely bad thing to do, the two aren't mutually exclusive.
She's going to beat Trump next week, but why on earth would you want to give him and his supporters actual ammo to make the case that it's a rigged system? Donna should be fired for that all by itself, but what she did is legitimately shady and makes the entire campaign look bad.