I believe it violates this rule more than a threatening gesture.IF - and I deliberately emphasize the word - you want to have an intelligent discussion about the Rule Book, then you need to quote the Rule Book and not substitute your interpretation of what words the Rule Book should have or could have employed. The precise Rule Book language is this:
No handler shall (1) carry exposed any training equipment (except whistle) or use any other equipment or threatening gestures in such a manner that they may be an aid or threat in steadying or controlling a dog;
So, the question is: Did the behavior constitute a "threatening gesture"?
During the period from the moment when the handler signals readiness for the birds to be thrown until the dog’s number is called, the handler of the working or honoring dog shall remain silent. Also, in all marking tests during such period, the handler’s hands shall remain quietly in close proximity to his body. A handler who projects his hand during such period, whether for the purpose of assisting his dog to locate a fall or otherwise, should be considered to have used a threatening gesture, and his dog penalized accordingly.