There was no way the whole Horde/Alliance Chopper thing was going to work out how they wanted it, people were going to complain whatever happened. Alliance got upset when Horde won, Horde felt superior for their voting prowess, and now that it's been announced that the Alliance can have their mount, albeit for a 'hefty sum of gold', a lot of Horde are upset that they're not so special anymore.
I admit I was a bit miffed, for the entirety of a second, when I read the news, but at the end of the day a mount's a mount, and the two factions can't ride eachothers'. The idea behind it was that the winning faction wouldn't have to pay for their mount, it would be free, so as far as I'm concerned the Horde have still won. And I also think it's better that the Alliance chopper is sold by a vendor for a bucket-ton rather than in the Blizzard store, at least it could stay exclusive that way.