I can see why he got rid of the Queen. Not only does she cut connection to the lesser ant shadows, making delegation a necessary and obtrusive evil. She also doesn't have a lot of fighting prowess, opting only to create more ants and the aforementioned delegate. Only attacking when she needs to, when she's backed into a corner.
Honestly, not worth the hassle of chain-command. Unless, of course, she was able to produce shadow ants. Like some kind of Protoss Carrier. That would be neat.