well, if the slim actually costs that much... I would probably guess they gutted it to the point of being garbage. They would of had to take out some major components in the slim model to reduce the price by that much. I'm think something just isn't being recieved correctly. If the article actually listed the conversation instead of just talking about it, this could make a lot more sense.
If you want to get technical, they could save a decent amount of money even just for the stripped down appearance of the slim. That could save them a few bucks on just that alone. Not sure about any technical changes but I'd imagine that there were more cost effective ways to do some things for the PS3.