Nobody's said anything about it. We don't even know if the Doctor considered recruiting him. So, it's hard to guess.
It's certainly plausible, and it would be neat and tidy if the in-universe reasons paralleled the out-of-universe ones. Just as Moffat wanted to bring Jack back for "A Good Man Goes to War" but couldn't because he was busy filming Torchwood series 4, maybe the 11th Doctor wanted to bring Jack for his assault on Demons Run but couldn't because he was busy killing all humans. But that's just speculation, and there's no way to know if it's true.