I hate to beat a dead horse, but I just thought I'd point out the text from the official NCAA Ice Hockey Rule Book.
Rule 6, Section 23, Part b:
"Hitting from behind into the side boards, end boards or goal cage is a flagrant violation."
PENTALTY -- Major and game misconduct or disqualification.
Just something to point out, because the way I read this, there should have been no question on what call to make in that situation.
I guess the ref's don't really know the rulebook the way they should.