John Wilkins sketches out PZ Meyers legal rights:
...a nonbeliever cannot commit blasphemy. To blaspheme, one must be within the set of belief and ritual contrasts of the faith community. Smearing pig fat is merely unhygienic behaviour to me, and throwing wafers on the ground is merely littering (and temporary littering at that, as it will be eaten by birds and ants pretty quickly. As sins go, that act of desecration is quite ecofriendly). This means, so far as I can tell, that a secular state cannot enforce anti-blasphemy provisions, as to do so forcibly includes nonbelievers in the faith community, which automatically means the state is not a secular state. It also means that pretty quickly the state becomes a one-religion state, but that's another matter.
So protection against desecration cannot be justified on grounds of blasphemy. What about offense? Clearly a society that lacks all respect for others will shortly fail to be a society; and it is good manners not to offend someone unnecessarily. The very term "polite" indicates this, as it literally means the rules of the city (polis). In a multi-moré society if you do not avoid constantly insulting people you will cause social disruption. But a state cannot legislate that standard either; such rules evolve rapidly and without regard to the special interests of all groups. The best one can do is have laws of disruptive behaviour and leave it to a current judge to determine if the behaviour is beyond the pale or not.
...while I might think that the original wafer thief's actions were disrespectful, in no way are they actions that should permit the kinds of reactions he, and Myers, have garnered. Sure, I think Paul's reaction to religion is often over the top, but he has that right.