If they lose where would you draw the line? This is part of Tatchell's concerns, e.g.:
Likewise, Muslim publishers (who believe that the Islamic prophet must never be depicted in art or drawings) could be legally pressured, against their will, to print the Danish cartoons of Mohammed that Muslims find deeply offensive.
I think if the publisher had a policy of not publishing anything which is likely to be offensive to religious groups, they would be fine. I think the problem would be that if, for example, they had published (or were silly enough to admit that they would willingly publish) cartoons that were deeply offensive to Jewish people, then they would be in trouble.
I think it's fair enough. You can't have one rule for one set of beliefs and one for another if they are both lawful. It's like I would hope that venues which are happy to host trans events would also be willing to host the Women's Place events. I don't want to see minority viewpoints shut out as long as those viewpoints are legal.