It won’t do any good unless you call the Issaqua headquarters and ask them why they pulled the book. It would be interesting to call and tell them that you are a reporter from an on-line publication and would like a statement about why COSTCO pulled the book and whether it is COSTCO policy to censor conservative political thought. Follow up with a question about the IRS targeting of the Teaparty organizations.
Costco sold boatloads of Sarah Palin’s books. Same with Rush Limbaugh's books and other authors. It's all about sales volume.