Senate guard would be a division that can recruit from GAR, but also can have handpicked guards from each division, tasked with guarding that division’s HiCOM and Senators, as to keep them with people they know and trust. (Would have separate Senate guard morph, with custom emblem for that division)
Every division already has a guarding company for that exact purpose. And RG exists as a GAR version of that. Senate guard is really unnecessary. If anything, it should be a company within RG.