IMO Quinn's demeanor behind the bench is intentional for the exact reasons cited. He likely projects a lot more emotion during practices and team video sessions; but like a TV/movie director, once it's "lights, camera, action", he doesn't want to impede the team's execution (even when flawed).
I totally get that when many of us grew accustomed to Parker's fire behind the bench as well as his ability to make in-game adjustments, a different coaching style despite coming from the same coaching tree will be scrutinized if results aren't met.