What if the teacher hadn’t done that? The overwhelming majority of schools don’t automatically offer algebra 1 before 8th grade, even for students as talented as your son.
Which math classes did he take in 6th, 7th, and 8th grade?
I wouldn’t push any student too far. I believe that is the decision is for the student to make, not the parent. If your kid doesn’t want to go for accelerated math, then we shouldn’t push them. If you want them to, remind them of the benefit instead of saying something like “you have to take accelerated math".”