Without having seen the play - who really knows...
The way I read it, the receiver was running across the field in front of a linebacker?
If the ball was not yet in the air and he got blown up, I don't think you have anything, he might not be expecting a hit from a LB, but he is a potential blocker and so the LB can engage him. With the ball in the air, the timing is important for me - the ball was not directed at this R, but is he defenseless? He is not concentrating on the ball, is not in a position that he would not expect to be hit... With a clean hard hit to the chest, I think I'm passing.