What did the defender do wrong? Why do we penalize defenders for doing their jobs? This is a charge all the way and not even close if you referee the defense.
Finally, I do not give a damn about an open hand vs. a fist. To me, this is one of the dumbest things we worry about at any level. We are not robots or have the same mannerisms to a tee. Why do we care about this stuff but to nitpick stupid stuff, but we cannot in any way talk about how to get plays right or what we are looking at. I wish we would stop talking about this kind of stuff. Yes, some things are important, but this is not one of them. No one but officials cares about this kind of stuff in the first place. We know if you have a block if your hands are open or if they are closed. And I have heard IAABO go on and on about signals being standard, but to me this is not the hill I want to die on. There are other things we should do or look similar, but with so many different people, body styles, personalities, you will have some slight differences. To me this is something for your local people not for everyone to nitpick. And at least where I live this is rarely talked about.
I remember when I worked the State Finals the last time, during my semifinal game I had an official/assignor call me about my directional signal. I tend to give "one finger" instead of the palm. I was told that "This is not a college game." But the reality is that college does not tell us how to signal in such a specific way and the people I worked for did not say a thing about may signal the entire weekend. Well, I worked the very last State Final in the State of Illinois for boys basketball working the highest-profile game. I say all of this because if my signals meant that much in that kind of way, I would not have worked that game that was for all the state to see. We worry about the wrong things and often things that do not change our basic communication or the ability. But if I talk to people about how to call certain fouls or philosophy, we get the purest come out and tell you the rule. There is an art and a science to what we do and there is a reason why some of us never can get anywhere because we are worried about something that does not help us do our job in the end.
End of soapbox.
Peace