The reason for sending a suspect to a third country rather than to the US, according to the diplomats, is an attempt to avoid highly publicised cases that could lead to a further backlash from Islamist extremists.
This is probably true for the US, but a cooperating Arab government may see increased Islamic extremist/fundamentalist anti-government activity to the point of rebellion. It would be wise for the US to use the newly reinstated policies of rendition ect. to prevent the destabilization of these cooperating governments.