Not misleading just my opinion...
He should take it to the genius bar to get a second opinion or....
You could help him with your opinion and he can do what he feels like

Is it hot?.... Is it really hot? [Gmm reference sorry lol]
Jokes aside it's normal.. unless it gives an error that it's too hot and disables usage until some time while it cools off which usually happens if you leave the iphone in the sun in your car while gps tracking...
It's passively cooling itself so don't worry it's working like a hand warmer for you while maintaining it's temperature.
If you still have doubts take it to apple store and a temperature monitoring device with you and show it to a genius....
He will probably send you back but it will give you peace of mind 🕊