the controller
Pull your head in dude, why should you log it when you are not flying and you are not giving instruction? The next step from here is logging time sitting in
23A in a 777.
I too am an instructor, but i don't log time every time i am sitting in the left seat of an aircraft with another pilot.
There are enough people in the industry with a bunch of dodgy hours in their logbooks as it is, do the right thing and don't log it.