I kept on reassuring him that his report card was ok
I think his report was excellent, don't you? He has reached the expected level of performance as a Grade 2 student, when he is only 6. Of course they are using words like "outstanding".
He is being scored according to his grade, what more can you want? He is already performing alongside with older children, yet you want him to exceed that too?????

What is your role in his reaction? I mean come on, you give him extra work in the school holidays, you are extremely focused on his performance level and scores and have questioned if you push him too far.
I think a 6yo crying over a report is your answer.

Maybe you should have celebrated his report with him and pointed where they had written exceptional and outstanding instead of questioning the teacher.

I know you only want the best for him but maybe you can lighten up a little and he will follow your lead. It musn't be nice to be stressed like this at such a young age.

xoxoxoxoxo