Well, see, I don't know about that.
JT needed to show Rupert, James, Amber and Candace he could be trusted, especially with the way he blindsided them a week ago.
If he got rid of James, it'd be Rupert, Amber and Candace in one alliance, Tom, JT and Colby in another and who's to say Rupert wouldn't be so pissed he'd convince Colby and Tom to boot JT next?
At least this way, JT moves himself up in the pecking order of the tribe. Colby is, right now, clearly the next to go and that then leaves Rupert, Amber, JT, James and Candance. JT could easily have an all-guys alliance at that point since Amber and Candance seem on the outs anyway and could then convince Rupert to get rid of James assuming the injury is still there (And/or he could tell Rupert the whole 'You want to go to Final Tribal with someone who has already won').
Not to mention, once these guys get to the merge, I think it's going to be every man for himself. Russell clearly is on the outs in his tribe and they're known as the villains for Pete's sake. You just know a handful of people are going to be looking to break tribal lines.