You beat up and leave Gallywix stuck in a suit of armor at the end of the Goblin Heritage quest. Gazlowe getting the job is a separate thing. It’s actually kind of weird because it contradicts what’s going on in the world at the time.
“Gallywix ran off with Sylvanas!”
“What? No he didn’t, he’s stuck in this fused G.M.O.D and Hobart Grapplehammer is wringing every copper he can out of him.”