The mall is a private property.. then yes.. they have every right to do that, just as you have every right to try another mall or do your shopping elsewhere.
that is the private company that operates and leases the mall in question, there are contacts on that page you may be able to get in touch with and speak to them about policy and notifying you are legally carrying. Maybe you can make a difference and a change.
Hope this helps!
And on the mass people in the forum meeting up for an OC event at a mall that has expressed through security that it doesn't want firearms in it? Personally I would not want part of it as there are other manners of settling this debate than o push our view on people forcefully. It would 100% end up with police and a big scenario that would maybe be avoided by alerting the property management and settling it in a professional manner, just my .02.
Another thing to think about, it the privately owned businesses in the mall, they would also have the right to ask you to leave the store space they rented. This may be a long fight to take on...
Disclaimer: I agree with the OC movement and I agree that it is legal and a right, I OC'd for years before my CDWL - still do on occasion.. I am not saying to be passive on the subject, only practical and professional about te scenario. you may gain more ground...