What Would You Do?
A different slant, here in Texas the owner can carry handgun in plain sight on his premises, his employees may if he permits them to, in which case the BG likely gives the place a wide berth.
On the other hand you might get in a stance to draw, announce, "I am armed and you drop the screwdriver and lay face down on the floor". The BG will likely tear down the door exiting the scene.
And then you may just have to shoot him if he pursues the matter,