I do not see how a metal detector is going to stop someone willing to shoot there way in as the shooter in Orlando did. Now, if law abiding citizens are allowed to legally carry defensive firmware we could shut this type of activity right down. I know it sound a little like the wild west but when it takes law enforcement 15 to 20 minute (or more) to respond to and active shooter event I do not see a better solution.

If you can't trust your co-workers you might consider finding an organization that only hires trustworthy people ;)