I'd love to go into detail again, but it would be the 1000th time I've done so.
So, I'd encourage a search here to gather a plethora of information on this subject. The lead trainer is a lead idiot if he doesn't realize that cardio performed a certain way, coupled w/precise protocols for eating to support anabolism and stave off catabolism, is a platinum way to lose bodyfat and PRESERVE lean mass, then he's very uneducated.
I'd let him believe what he wants, and keep doing my thing.
You can't please everyone, nor should you aim to try.
~SC~