We don't have experience with the actual AOPS course, just with Alcumus. However, you may want to remember that 2 hours a day for a summer course will probably translate to less than an hour a day for a school year course.
If you believe that he has mastered Algebra 1 and Geometry and should be in Algebra 2, you should approach the school to have him tested to prove mastery of those two years of math so that he can be accelerated. There may be other options than AOPS once the school approves an acceleration.
