I would definitely bring up the fact that it's very confusing and counterproductive to have him lose the next day's entire recess for one thing at lunch, when he's working so hard at everything else. He's just going to give up trying.
And the teacher(s) seem to be completely against him in everything. It's a perfect example of what I figured out in high school -- if you make a good impression on a teacher at the start, you can pretty much do no wrong in their eyes after that, but if you start with a bad impression, nothing you do is ever going to be good enough and you're going to be in trouble for everything. Fortunately for me, I was on the good side of that equation when I figured it out, but the poor boy who was on the other side had a heck of a year. Your son's teachers are convinced that he's nothing but trouble, and they will not see anything good in him. I'm not sure I would even bother staying for the rest of the year, if you had the means to keep him home and just start over next year. They're doing more harm than good.
