No surprise there so far, on most 2.x devices you don't get multitouch in the webkit browser although the device can recognise more than one touch. There is an (early) polyfill available, which works for OpenStreetmap and GoogleMaps, but not for the link you provided :(
Thanks to Sam007's clarification the general issue cannot be related to 2.x (only). So it all narrows down to the touch event implementation of Android vs. iOs.
First thing coming to mind is that Apple introduced (proprietary, non-W3C-recognised) Gesture Events in Safari, which to my knowledge no other browser out there implements. If ArcGis only honours those events, you will be able to solve your problem writing a "simple" touch* to gesture*-Event converter.
I'd do it myself, but i don't own any apple devices. What i would do next is to enhance your example page with a debug window and catch all the events you could think of. Find the differences between Android and iOs, and you're halfway there to make ArcGis work as expected on Android.