Well, I can certainly sympathise with him--I have quite a few of those instances stuck in my head from 20-30 years ago; I am a perfectionist, and I tend to expect other people to want to have things correct, too. But for what it's worth, the only one that I truly regret to this day is the one that I didn't speak up about.
In one case, I was taking the employment tests for Kelly services and was graded wrong on an answer which was right. I asked for a dictionary and showed them, and they would not correct it and even told me that my "combative" attitude would not serve me well as an employee. I told them that I hoped that people would prefer for me to write and type correctly for them.
In another case, I had a college class where the answer keys for tests fairly regularly had wrong answers, and when I challenged yet another one the professor told me he was tired of "carrying me" and refused to correct it. "Carrying me"--when I had a 4.0 gpa and was only questioning an answer that meant the difference between A and A- anyway. Silly me, I thought the point of classes was to learn things, and to that end it would be useful to have the right answers on the test keys. And that answer might make the difference for someone who needed that point, too.
But the one I still regret to this day is that I did not challenge a judge in a speech/debate tournament. She fell asleep during our round, and I still kick myself 25 years later for not walking out on her.
So yes, frustration tolerance is something, and I probably don't have enough of it to judge its merits. But it's also something to stand up for yourself and to stand up for what is right and to stand up for your education and insist that knowing the right answer is worth something and that knowing how to think and come up with another equally right answer is worth something too. It would probably also be useful to learn how to write sentences that don't take up the whole paragraph.
There is a great deal to be said, however, for learning the Japanese concept of "saving face", which is where that "perhaps I misunderstood" and "just to clarify" comes in. It never hurts to start a question with "I'm sorry,..." as in "I'm sorry, was it the size of the planet they were asking for, because I was thinking that the orbit and the atmosphere and the tilt of the axis (or whatever) were more similar in Venus...."
I say this all with the strongest conviction that my DS7 will never master any of it in a million years.