90+ is way too many. Does your son have an offer or commitment? Are you risking that with the elevated pitch counts?
HS ball is not worth long term issues later. Period
100x Age is the annual guide but I wouldn't expect anyone to go out of the gate and go above 65 for the first few weeks. Not worth the risk in early season. You need time to build and ramp up to those higher pitch counts and loads.
No fair to your son and his arm to be over used and not fair to expect a kid to say "yeah coach, I should come out". Expect more from the coach, whether you know him or not. I would definitely say something.
In many years of travel ball, we had limits and it didn't matter what the score what or who we were playing, even for a championship. We pulled kids to protect their arms vs chase $1.95 plastic or a stupid ring.
HS doesn't matter. It's barely palatable, if that, and is just reps to get you ready and keep you healthy for Summer ball. You need to be injury free for summer. Pitching too much too soon, risks summer. As a senior the situation and timing may be different.
I get the pressure if he's chasing an offer or scholarship as a senior, but typically, you'd know by know if he was going to be playing at the next level. Spots still left D2-3, JUCO and NAIA for a stellar kid.
Scouts told us when we traveled to Marietta for a National Championship. "If there are twins, of equal baseball ability, separated at birth. One grew up in Ohio and the other grew up in Texas. We will take the kid from Ohio 10 times out of 10. The kid in Ohio had to take a break due to weather. The kid in Texas could play year round and comes to us injured or worn out." Something to think about. Luckily I've been documenting 1st pitch of season, last pitch of season and break since my son was 9. We take 2-3 months off at the end of summer and 3-4 months off in Winter. Luckily he also plays basketball, so there is a break and he doesn't pick up a ball early, even for HS tryouts. No sense in eating into his break from fall getting him ready to pitch for a tryout to then not play for another month. We can't play 2 sports at the same time in Texas, or at least at our school.
We were lucky. He was starting varsity as a freshman so he's a known good. Doesn't hurt this year that he's a junior, and the only D1 commit at our HS. I said something early when he was a Freshman and the first varsity game, after a few JV games, he went 87 pitches early in the season. I have no problem pulling him from the team and putting him in regular pitching lessons/sessions if they abuse or over use him. They take it very easy on him after transition from Basketball. He pitched only 1 inning the first scrimmage week. 2 innings the next. Then 4, then 6 and they pulled him at 82 pitches. We're a month in and feel way more comfortable with them taking their time on his load. Also helps that GT Pitching Coach called into the HS and reminded them to take it easy.
I wouldn't NOT say something. Again, it's HS. not worth the RISK or small injury that could get worse... My $.05