Far from an expert, but I wouldn't place any raw cat food in a pan to "cook" it as vaguely as he describes...I'd probably be more careful about how to's of warming up the food from the fridge to body temperature, but again, that's just me.
There's just too many folks who'd just "do things" without enough research or looking things up.
Slightly cooking the raw is a transition trick and is not intended to be done long term. He suggested giving the slightly cooked food as a treat, not the entire meal. Or use it before a regular meal when the cat is really hungry to see if you can get them to give it a try. I see nothing wrong with it as long as it's not used long term as a regular diet.