The best time to be disarmed is ....... NEVER. They DO NOT have the right to disarm you absent RAS. Also if a business has a problem with me OC, I would much rather just leave than do business with them. Especially if they send the cops instead of just asking me themself.
Edit: Also, "Are you detaining me or am I free to go about my business?" would have been a good response to him asking you outside.