My impression is that the liability issue - from the perspective of your employer's insurer - will rule the day.
If it is the case that cost of liability insurance when all weapons are "banned" on the premise is $x, and the cost of liability insurance when CCW is permitted is $(x+y), then if y > 0, the company needs to ask whether the benefits accruing to the company are worth the additional cost. My guess is that makes the outlook pretty bleak, and the insurance company would specify rules it finds acceptable for a particular level of coverage.
Mike