How do you do multitouch with a stylus? Do you put the DS down and use a stylus in each hand like a knife and fork? So you wear little styli on your fingers like finger picks for a guitar? Or do you use your... fingers and smudge up the screen? Nuts to that idea.
The touchscreen is more or less like a mouse for a portable. How often are you using a PC and think "damn I wish I had two mice right now"?
It comes across as an idea that sounds cool but no one can really think of a useful idea for it. The most common idea is one where people suggest you just put the buttons on the screen and then you can have whatever layout you want. But think about how hard it would be to tell what button you're on when everything is a flat screen.
Please tell me you are joking. Ummmm, maybe you would use multi-touch with your thumbs or maybe with your thumb and pointer finger on the same hand. Who in their right minds first thought is to grab a second stylus and use it like a fork and knife? I mean it's not like an iPhone (the most popular usage of multi-touch) uses a stylus.
There could be some gameplay concepts that require you to use the stylus in one hand and use your other thumb on the screen at the same time, but to compare the concept to using a second mouse on my computer at the same time is just not well thought out.
multi-touch is more like using your hand to do with out a mouse since you don't have any buttons to click.touch is like having a mouse for our portable, multi-touch is like also having buttons to click.