Getting fired for breaking dress code: no one gives a flying _____
Getting fired for breaking dress code, and "God" or "Christian" is mentioned: OH MY GOD STOP THE PRESSES!!!! Put it online! Get petitions! Call the congressman! File lawsuits! It's WRONG!
Now if they allow other non-business buttons, that would be different... although considering the button itself is not religious in nature in itself (well, it is and isn't, the phrase is in schools and in govt. meetings, so it "isn't"), I would say it appears to have nothing to do with religion, rather a angry employee who got fired trying to get back at the company.
Also, as the article says he was offered a company approved "united we stand" he refused -- so he really is not supporting the country, rather it was the employee wearing it for just a religious reason. Basically, the kid lied.