For goodness sake…

Not all malls have declared guns prohibited.

But use your brain…just change the hypothetical location from a mall with the correct signage to prohibit guns to main street of a small town.

Or heck, think about this - the mall posts the signage and guns are prohibited. You are in an open carry state. Guy walks into the mall with a hand gun in a holster. Did he walk through the door because he missed the sign, and is just used to carrying, or is he there to shoot the place up?