Re: Anger on the mat
As others have pointed out, the problem is entirely with him. (which you clearly recognize.) I would not continue training at a dojo where such behaviour was tolerated by the sensei/dojo-cho. Stuff happens, there are always "problem children" in a dojo -- it's the overall attitude, and how it is handled the matters.
At my dojo, when I'm teaching class, especially a class of very new people, when I make a mistake (eg, uke doesn't fall, or the technique is muddled) I think it is a great opportunity to make the point that Aikido is not "canned". I'm not doing a stock thing against a stock attack. If you're training at a dojo where [it appears] noone is making mistakes, or where the instructors cover their mistakes... you're instructors are poor teachers. Growing means making mistakes, and being surprised sometimes with what you *are* able to do.