You're forgetting one key point... it's not a publlc store. It is a private corporation owned by it's shareholders who are entitled to set a policy of "no guns." They're not eliminating your second amendment rights, they're just telling you to exercise them elsewhere. The same holds for first amendment rights. You think you have them? Try going down to the local mall, getting up on your soapbox and speaking out against the lack of constitutional rights (or any other topic). Security will request you stop, after which they will call the police. If you still refuse to stop you'll be arrested for criminal trespass. Now when you get to court, try to continue your tirade against the Obama aministration. You'll be warned once or twice an then charged with criminal contempt of court or obstruction of governmental administration. That's just the way it is. You have no first or second amendment rights on another persons private property.
Anyone remeber they duct-taped Larry Flynt's mouth in court to keep him quiet?