I don't think its stupid, its just working within the confines of what Apple have provided.
The question is, if everyone jumps on this 'solution' and it becomes an issue, will Apple 'fix' it by slowing down these busy wait threads, or provide an option for devs to do it 'properly'
The best approach would be to treat "High Performance" as a system-controlled attribute like "Can Read Location Data"; the app can make a request for a performance profile it's designed against, the user gets final say-so, the OS records the user's decision and re-uses it for future launches.
This gives best of both worlds; users who need performance pick it, users who don't need/don't understand get to be kept safe by Apple's scheduler. Apps get back the state, so they can render a different icon or something to indicate "Hey we'll do our best but your hardware may not max out because scheduling wasn't built for this task"
It's not about safety but battery life. I don't think bombarding non-technical users with all kinds of tradeoffs is the best option, but this seems to be a niche app case. Maybe an attribute could work, but it's difficult to say if that guarantees anything. Phones can overheat too...
I don't think its stupid, its just working within the confines of what Apple have provided.
The question is, if everyone jumps on this 'solution' and it becomes an issue, will Apple 'fix' it by slowing down these busy wait threads, or provide an option for devs to do it 'properly'