Because it will appear as sour grapes or personality dispute/getting even. It needs to be done now, not after the fact.What's wrong with reporting after the rotation is done?
Doing the right thing sure seems to be hard for some of you. If the lab tech dropped the N-word, referred to a gay patient as a f*****t, or called an Orthodox Jewish patient a k**e, you'd still advise waiting until the end of the rotation??
There are laws that protect people who complain to HR about these things, BTW.