The problem I think is that Wal-Mart execs bought into the wrong diagnosis. They didn't have loses because of a boycott by the left. More likely, it was because the left infiltrated their staff, and Wal-Mart helped them do it with pc policies. Then, these lefties set out to treat the customers badly. I had a Wal-Mart cashier quiz me about stuff -- seriously -- and I innocently mentioned a Christian college we had visited over the weekend. SHE WENT ON A VERBAL RAMPAGE AGAINST THE COLLEGE AND CONSERVATIVE CHRISTIANS. I was very mad, but I just took it.
A company can't discriminate against employees or potential employees because of their political views. I don't know if it's against the law, probably not, but it's certainly bad business.
That said, entering into a "debate" about religion with a customer is just plain dumb.