While I agree with your argument, do you realize you are unwittingly showing them the way to keep ALL firearms out of their business. Let them do their own homework.
Every time we challenge a business, they become less ignorant of the methods to keep firearms out. Not to start a debate, about OC vs CC as it has been done enough, but could you have just CC'ed in this environment and still accomplished your objective of protecting yourself?
Concealed is concealed and they would not have every known you were carrying.