I have often thought this was the case, not only in basketball, but football as well. The thought being 'there is no way Northwestern's Cornerback X could cover Ohio State's Wide Receiver Y' without it being interference; or in this situation which would say that of course it was a clean Ohio St. block, because the other player was from NU.
Its the same bias shown by announcing crews who suggest that we have to play the perfect game, or a smart game in order to win, because of the discrepancy in talent. Its just there and I am not sure if it ever goes away, just perhaps shifts from team to team based on expectations.