Quite possibly the decision to abandon Benghazi was done for any number of reasons that had nothing to do with derailing the FBI investigation into what happened there. That effect just happens to be an unfortunate coincidence of what was surely done for other, pressing and legitimate, reasons.
Likewise, the sudden deployment of a member of the National Security Staff to Iraq is explicable in terms of the difficulties that nation is experiencing just now. It is merely a coincidence that this particular NSS member happened to be one who corresponded closely on Operation Fast and Furious with an ATF agent who just testified to Congress about that program. The fact that this member of the White House will not be available to answer Congressional questions about the role of the administration in that operation is just a coincidence.
It would be improper to suggest that such significant matters of foreign policy were being subordinated to political considerations. No one would believe the suggestion anyway: it's impossible to imagine the administration acting that way.