Annual topic - and amazing transition from 10 years ago. At that time the counts that got people commenting ran to 125 and as high as 140/150. There was great debate about the value of pitch counts at all.
Now folks do not doubt pitch counts but actually start getting alarmed on numbers that weren't even on the board in 2010. People would have laughed you off the board for hand wringing over 90 pitches.
With all that said - HS pitching is usually pretty shallow and whoever is #1 option is almost always going to get more leash from a HS coach. The tricky part is how receptive coach is to any conversation on player utilization. I suspect when it comes to arms the door is far more open now than it once was. Assuming that is so - it would be better for the player to discuss with coach the limits and to do so before games.
If pitcher says he was gassed for last 15 pitches and was coming up in zone - he may have doubled the stress on his shoulder as mechanics broke down in those last 15 deliveries which if repeated all season may end up badly.
I used to ay then and I say now - that arm should last a lifetime. No HS glory is worth a life of pain from a fried arm. Injuries will happen but reasonable precautions regarding over use mitigate against the worst of it. Almost no HS game is ever remembered by anyone that was not a participant and even then most blend in in as little as 6 months. Any game that is likely to be remembered will happen at the end of the season and not in the first 2/3 games of the season. So settle in - be safe and avoid pushing too far and the games will take care of themselves.