Maybe he should try out the class. You'll never know if he doesn't at least try, and you certainly don't want regrets. I believe most schools have an option where you can drop an AP class within the first 2 months without any problems, so if he hates it he could always drop.
Speaking from personal experience, I took AP US History my junior year and dropped it because the workload was insane. I was staying up until 4am some days to finish reading chapters, and we had reading quizzes every week. I hated it.
I took AP Government my senior year, and I really liked it. There was reading and reading quizzes, but not as much as the AP US history class. Also, there were no essays or writing (because the AP test doesn't have any essays).
It really depends on the teacher. It's quite possible that if I had gotten another teacher my junior year, I wouldn't have dropped the course. I recommend he tries it out and sees if he likes it.