So lets agree that his $15K device worked at one time and he verified improved FR with measurements and listening.
Great. So it's not a snake oil product. And yet you'd quoted Amir saying it wasn't a snake oil product and implied it may as well have been. That's the sneaky part I was getting at.
As to Amir's views on crossover parts - he's either right or wrong. You don't decide this by continually calling him arrogant. He walks the walk - puts up objective evidence for his claims. Anyone is welcome to do likewise in debating any of his claims. As for room treatment, again...you can take his claims to task...or not. But all the stuff about "ego" is a sideshow, and one only concentrates on that if they don't have a substantive argument against the claims.
I believe Amir linked to an ASR thread in which his arguments about room treatment are being critiqued in various ways, by people adducing technical claims, measured evidence etc. So, maybe read on it, make up your own mind.
My own room has forms of room treatment, and I enjoy experimenting with it to achieve various goals.