The difference in the poll results may simply be a function of the reality that a pious Muslim is obligated to engage in a ritual prayer exercise several times a day, while a Christian is under no such obligation. Why would a Christian possibly need to have a prayer space provided at his/her workplace?
The headline proclaiming "huge bias" is irresponsible. Religious obligations differ. It's like citing a poll favoring allowing Christians to take off Good Friday as exhibiting "huge bias" against Muslims.