There's nothing in the world wrong with flying from the right seat.....every single airline in the country does it. When I hired our copilot, I wanted to type him right away, but he was about 50 hours short of ATP mins and had no written, and we all know you can wipe your butt with a commercial type rating but that's about it. Insurance said he had to have school before he could touch the thing, so we sent him to an SIC initial at Simuflite, and we're gonna type him at recurrent next year. No contract. If you treat your pilots well, you don't need a contract.
Right now, there are only 2 pilots, (him and I), and he flies every other leg from the right seat. Once he gets some time in the airplane, figures out that it's not a piston single, and learns how to be a good FO, then we'll be swapping seats. He flies left seat anyway on empty legs, but there aren't many of them at all.
Point is, the guy that's complaining to you is a ******************************nut. Tell him to quit his bitchin and pull the dam-n gear. I've never flown a Gulfstream, and I sure wouldn't mind pulling gear in the thing for a while before flying, especially with the boss on board. You gotta learn how to fly the right seat before you can fly the left. Tell him to go kiss a monkey's butt.