400A, I fly both seats as well... though right now, I'm flying mostly right, yet I'm the one signing for the plane. The tiller is on the left too. Insane, right?
I've landed this airplane once from the right seat and that's it... I maintain my right seat quals in the sim on every recurrent. Do I feel comfortable in the right seat? Absolutely. I can always take the controls and safely land the plane just as I can do from the left.
Why are things like that? Because when 2 'trainees' went to their initials, our management company in their infinite wisdom decided not to give them right seat checkouts therefore limiting them to the left seat. It's the GCAA thing. These 'trainees' are highly qualified former G-IV captains... and guess what? They cannot sign for the airplane until they accomplish their line training as directed by the company, nor can they sit in the right seat/swap seats either until their first recurrent.
Are you still vertical? You didn't get a heart attack yet? Yes, I'm signing for a 50 million dollar plane from the right seat and flying a billionaire owner. He's aware of it, and he's glad. Why? Because he was briefed properly on what is taking place, and he's very supportive of it.
I think this whole left-seat hogging is an ego thing, but also a fear thing. These pilots know damn good and well they would do just fine flying from the right seat or taking over if there is a need. Instead, they don't want to look replaceable to their boss...