I've heard him say that before a while back, and he's on extremely shaky ground to make such a claim. They're basically exploiting the technical ignorance of some people in order to make a sale, and even if someone is happy with their purchase it's something that they may not have needed to buy in the first place.
What a few people may not realise is that EVERYTHING of a lower resolution than a particular LCD TV's display has to be upscaled anyway otherwise you wouldn't get any picture whatsoever! (Think about it.) Upscaling is simply the process of converting a standard definition picture (eg. Freeview, satellite or DVD playback) to the number of dots that your LCD TV happens to have (720 or 1080 rows of pixels (or colour dots) for HD), and an upscaling DVD player simply does one stage of the process within the DVD player itself instead of the television, but that doesn't mean that the DVD player will do a better job of upscaling than the television itself - sometimes you're better off using an RGB SCART connection and letting the TV do the processing instead.
(Incidentally if you have your television's HD overscan mode switched on then the television will still adjust the aspect ratio of the picture even if your DVD player does the upscaling.)
