Yeah, I dont think these Gnomes will be an allied race. Supposedly this culture worships machines, and you're actually considered better the more robotic you are. That doesn't really jive with either the alliance or the horde. It doesn't even jive with Gnomes themselves. So this sets them up as potential villains, and considering we're bringing this Horde along means they could be major villains.
Also the thing that makes them unique (robotic limbs) would be hidden by armor. Making them a poor choice for an allied race.