Re: BS in fellow aikidoka
I agree with Matthew. This guy at your dojo represents a chance to sort things out. Maybe a chance to subdue your fighting/competitive/reactive mind (something we all have). My Sensei says that "uke is never wrong". He also says that if you can't do it , or if you make a mistake, that you just have to "cop it sweet".
Having said that. I believe that you are well within your rights to request, under the banner of harmonious training practices, to have your wrist held less tightly. At least in the beginning, until you can get the technique happening. Then you can start to take up the slack.
Training is a form of forging right?! When a sword is forged the metal is heated and hit with a hammer. At the dojo we should experience a bit of "heat" and get hit with a "hammer" every now and then. If we don't experience hardship sometimes then training has become too easy. If it were easy then every man and his dog would be doing it!
Good fortunes to you.