You said it was wrong, not that you disagree with it. Also a big difference. Costco sets it's own policy, and it's up to them to decide the right and wrong of it. Not you and not me.
It's Costco's right, up to a point, to decide policy on it's property and it's up to me to decide where I will spend my money. And I won't spend a dime of it at any commercial interest such as Costco which uses a part of that dime to support every liberal politician and every ultra-liberal, unconstitutional "cause" that comes along.
I would be astonished if Costco didn't ban lawfully carried guns in it's stores since it no doubt spent a ton of money lobbying against passage of the CCW law in MN and every other state where it does business. That's their right, and it's my right to tell them why I won't be patronizing their stores. What does suprise me is the amount of support shown here for the well known liberal slant of Costco's hippy-dippy liberal management people on a forum that was almost exclusively conservative when I found it 8 years ago. I can and do acknowledge the right of others to act in a manner that I disapprove as long as that act is within those rights protected by the Constitution, but I don't have to support those people or their acts with my commercial patronage.
To see where Costco's and it's competitors' political donations go check THIS out. If you don't have time here's a brief synopsis of contributions by a few major retailers:
Price Club/Costco donated $225K, of which 99% went to democrats;
WalMart, $467K, 97% to republicans;
K-Mart, $524K, 86% to republicans;
Home Depot, $298K, 89% to republicans;
Target, $226K, 70% to republicans;
Circuit City Stores, $261K, 95% to republicans;
Rite Aid, $517K, 60% to democrats;
I disagree with it. I think people should complain to Costco management and try to get them to change the policy.