I feel your pain - we live with a system that offers no flexibility whatsoever within a given track, so we usually scramble to find challenge and enrichment in fields that aren’t mandatory subjects in school or at least not within his track. So far, that has been lots of computer science, robotics and Ancient Greek, of all things...and music and sports, outside of school, to keep him social and busy.
It’s hard if your child wants and needs more in precisely those mandatory subjects. But if the school will do what the school will do anyway, I see no reason not to enrol your child in whatever math class they are interested in and can handle. I assume your child is old enough to understand that there is no point in then complaining that math class in school is even more boring as a result - they’ll just have to suffer through the repetition, make sure they collect their As and don’t alienate the teacher on the way...
I do not want to go all Waldorf on you, but I’m wondering why you wouldn’t want to save up the accelerated class for extra stimulation during the school year, and use the summer vacation to make sure that your child gets lots and lots of outside time, exercise and maybe art or music or whatever might float his boat. I am assuming you live in Boston, so remember, winter is coming!
I just heard today that DS11 will have to start mandatory computer science next year in 7th grade. That somehow wasn’t on my radar since CS was strictly elective back when I was in school. I recall now that DS11 has frequently helped DH prepare the tests for DH’s computer science class that he teaches to 10th or 11th graders...that should have been a clue....and kind of predicts more boredom down the line LOL.