In the context of your school, this looks rigorous to me. While I had a little debate with gibby in another thread about just how many applications Harvard may get from Canada, I’m sure MIT gets enough that it is aware that few if any Canadian high schools offer dozens of AP classes beginning in 9th grade, and does not expect Canadian applicants to show up with 8-10 AP classes under their belts.
The initial determination of rigorous curriculum is made by whoever at the school completes the Secondary School Report that accompanies the application. In the U.S., usually it’s a counselor of some sort, but lots of schools abroad don’t have someone with that function, and it falls to some other administrator to do it. There’s a place on the form where the official has to tick a box describing the applicant’s curriculum as “most rigorous” or several lesser choices.
So the most important thing to do is to figure out who is going to be deciding which box to tick, go to that person, and ask him or her what he or she thinks. (And use the opportunity to sensitize the person to the fact that there is only one acceptable choice to make on the form. The question isn’t whether the most rigorous box will be ticked, the question is what courses your son has to take in order to justify ticking that box.) I expect the answer will be that you are fine.
And, no, AP courses are not really equivalent to college courses, certainly not at MIT. It may accept them for placement purposes in some science or math progressions. I don’t know whether you can get actual credit at MIT for AP classes.