Yes, Gej has great power in his possession, but he can't achieve much without full co-operation from the north, Its obvious loads of the so called northern leaders are pro Boko Haram and want to undermined his authority, If he send the army into the north, they will be the first to accused him of militarizing the region and all sort of bulllshitts.
I would suggest he leave them to their lots until they are ready to co-operate with him to solve the Boko Haram issue.

When America and Nato did'nt have the co-operation of Afghaans and Irakis they were unable to tame the insurgence and I don't expect Nigeria/GEJ to work magic without co-operation from the northern region to uproot boko haram.