That’s the point.
Overall SQ (dialogue, Surrounds, etc.) probably has more to do with the actual sound mixing than whether it’s DTS vs ATMOS.
Maybe sound mixing with ATMOS is different than mixing with DTS.
Maybe there are advantages and disadvantages, pros and cons.
Maybe a lot of things.
So yeah, maybe there’s probably a little bit more going on.
I’m sure he doesn’t owe an explanation. But if he has tried mixing with ATMOS and doesn’t like it, then most of us would understand.