1: Concealed means concealed. No one will know you have a gun unless you have to use it.
2: It is probably a good idea to carry if working in a high risk of robbery job. Working in a high rise office with limited access probably does not qualify as high risk, nor would a department store. However a drug store would qualify.
3: In the end there are two choices: One is follow the employers rules, get robbed/ threatened with a gun/ get shot. And the other is carry concealed, risk getting caught, get threatened at gun point, live to tell the tale, get fired.
If I was the R PH guy and was looking for a job after getting fired, I'd make it known that had he not had a gun, he would likely not be looking for a job. He also would not likely be able to wake up and go to a job either. . . .