Taylor Swift is said to be worried sick for her tough guy beau, Travis Kelce, after a man threatened to shoot him at a Morgan Wallen concert. RadarOnline.com can reveal the Lavender Haze singer is pushing Kelce to beef up his security – even on her own dime – after suspect Aaron Brown was charged with making a terroristic threat. Brown allegedly went on X to declare if the tight end star and his Kansas City Chiefs quarterback Patrick Mahomes were brought onstage by Wallen at his recent Arrowhead Stadium show, Brown would “take the f—ing shot. F— them!” The threat delayed the August 2 conce…