I think there is an advantage to being in the booth, let the position coaches do the on field corrections/motivation.
I would imagine that the tech at a desk is a little more robust than running up and down the sideline.
He needs to be able to focus on the next call, easier without all the commotion, remember he is a rookie coach when it comes to play calling.
He is not the tallest guy, so being able to see the whole field is important....
I'm sure someone on here will rip him for "not being a real" coach, so I'll just say I'm good with it.