Probably because TeamFourStar wouldn't ask for much in terms of pay. They were only in one scene, too.
The english voice acting in Kai wasn't even that bad, though.
I can't stand watching the original english dub regardless, the Faulconer tracks are spammed way too much even outside of the Saiyan and Freeza sagas. The Perfect Cell VS Super Vegeta fight is a great example of why the Faulconer tracks are insanely annoying, the moment any of them make a move Cell's theme starts for two seconds, then stops as another track starts playing, then to another track, stop, cell's theme, back and forth. It's not like the scene is getting its own special score for a fight, instead there's this horrible cutting between synths every two seconds.