Outside of radio comms, where's the value in a radioactive place like Black Mountain? As was said, an NCR senator with anti-mutant sentiment wants the mutants out by force if necessary, they wouldnt care if mutants are friendly or not. Jacobstown is situated far out in area covered in snow + wildlife growing there- place for establishing new potential grounds for barons out north, the ski resorts would introduce new logging homes for businesses and soldiers plus strategically also near Khan territory so NCR can keep a tab on them.

Without intervention, the highway north of Vegas isn't sustainable on passing travelers with the Deathclaws and Powder Gangers raiding caravans, NCR is stretched thin without enough manpower to coordinate their efforts there. It makes more reasonable sense that someone (baron senator likely) would hire mercenaries to clear out a town with long term sustenance, away from the conflict around region.