As long as he has someone in the booth I don't think it matters much. It's may seem impersonal, but the birds eye view is a MUCH better way to break down a defense.
But with todays technology, TC can probably be told whats going on, and have plays put on a monitor on the sideline if he really has to see it.
Kind of like when they show a QB sitting down 1min after an INT looking at pictures of what the D formation was and what they missed.
Honestly, I'd rather see him upstairs, but that's just me.