Not trying to get the pile of bricks emoji, but...
There absolutely has to be a line somewhere between IUH foul and UNR foul. It doesn't take a huge imagination to create a scenario where IUH is bad enough for it to be turned into UNR.
FWIW - I have no heartache with this being a very fine line in the name of safety. Just because 9-2-1 & 9-2-3 mostly fit doesn't mean every possible "incorrect block" is IUH. Suppose a blocker decided to "block" by grabbing his opponent by the throat with both hands and driving him backwards with that contact? I'd immediately categorize this as UNR and not IUH.
Unfortunately, "the BLIND cannot see", but those who simply REFUSE TO LOOK, actually choose to not see, so their blindness is by CHOICE. Hands can wind up contacting the face in an endless variety of ways, those that do so satisfying the intent, or actual effect, of violating 9-2, as judged by the covering game Official as dangerous or gaining an unfair advantage, whether intentional or not, violate the intent & purpose of 9-2.
The antidote to avoid suffering penalty is clear & obvious for EVERYONE - Stay away from contacting an opponent's face, OR RISK CONSEQUENCES.
