First off its my buddy Baumer's setup, not mine. I use a simple swinging shelf to hold my stick.
Yes it is a free standing system, as he has it setup the chair is bolted too it.
With the chair all the way back its not hard to climb in and sit down. Then run the chair forward with the seat adjust system that came with the chair.
But the "Mini pit" could be used either way, attached to the chair or free standing.
The only issue with a chair that can be rolled up to it, is that you push yourself away when using the rudder pedals.
A small sheet of Plastic or Plywood with a couple of 2" holes cut into it for the castors on the chair to drop into would solve that problem. Would give you the best of both worlds. Would let you use a comfy office chair on castors, and would hold the chair in place while flying.