See, @Spiky is the one who knows me best. I'm almost useless at the important stuff, like swearing at stupid people.
A couple thoughts... I would have expected better of Dr. Sudan as well, as he is known for doing the DS. However, there are a few things in his advice I would agree with - first, we do need to make sure we get in enough protein, no question about that. Yes, carbs do cause gas, and many people with both DS and gastric bypass do become lactose intolerant. And excessive amounts of fat will lead to more poop, or very loose poop and/or oil slicks.
BUT the rest is not good, and as @Spiky pointed out, any advice that is identical for both operations has to be wrong for at least one of them. So just focus on protein, don't worry about the fat that comes along with the protein, and limit carbs, esp simple carbs. One of the great things about the DS is that you don't have to eat just lean protein, you can use whatever form of protein you like. You also don't have to cook fat free, or use artificial low fat foods. It's a much more normal way of eating.
And the only other advice I can offer about those classes is, when you meet other DS patients there, direct them here. Pay it forward.