If, after several meetings asking them to remove the offensive material and being given paid leave of absence, they still refuse to remove the offensive material, then yes.
That said, I think hp is silly to have such a campaign sucking up to diversity. And I understand your support of the guys beliefs. hp did what they felt they had to do. They have lost another customer because of it.
Who owns the cube? You do not, nor will you ever own your cube. The cube is provided as a gracious gift by your employer. I have worked for companies who did not furnish their employees cubes. Engineers spent their entire day sitting at a bench with lab gear. The cube is a benefit. It is not yours, and your rules do not apply in the cube. Where did you think that the cube was somehow your private property?
Should all those possibly offensive-to-someone pictures, quotes, statements all be barred or the posters thereof be fired as well?
They are, if I place some Playboy posters in my cube, I may be given a warning and the opportunty to take them down. If I continue to place them in my cube, I would certainly expect to be fired.
The fact that it was a bible verse is not important. The person went out of his way to create a harmful and threatening environment. He was warned not to do this, and was graciously given paid time off to ponder his decision. He took the paid time off, and decided that he liked abusing his co-workers. When you work for a company, you have a choice. Abide by their rules, or work elsewhere.