Simple. Because if you need a Mac Mini, a Mac Mini + third party 32" external monitor is still half the rumored headset price.I think they just mean that it could be used as a Mac mini. Why buy a headset and a Mac mini when the headset is just as powerful and could be used as a Mac?
Another BIG question is, can the headset be plugged in to power all the time? Or will it require swapping battery packs to keep it going?