I had not heard of the "Islam role playing" case before. You're right about the Snopes treatment being the most balanced - they usually are.

The main point I am trying to make is not whether this kind of teaching is actually a bad thing from the standpoint of a reasonable person. It's that bringing Christianity into a school on this same level would have brought the wrath of two dozen liberal rights organizations down on the school.

Maybe not two dozen... However, if the parents had gone to the ACLU instead of whoever they did go to (I couldn't discern that from the links you provided), that organization would have acted as promptly and with as much force as if the religion allegedly being promulgated were Christianity.

All that aside - one example, almost two years old and partially apocryphal (depending on which reportage one reads), of one teacher's misguided lesson and activity plan hardly constitutes a trend worthy of being characterized as
[ . . . ] the tolerance of the Left towards Muslim religious activity in public places (like schools) [compared] to their intolerance of Judeo-Christian activity.

It's not the fault of constitutional rights groups that the overwhelming majority of misplaced evangelizing -- and subsequent legal action against it -- has been Christian. It's an accident of history that Christians of one sort or another are still the majority in this country; it's a tenet of faith in some of those varieties of Christianity to proselytize (Jews are expressly admonished not to proselytize; I have no idea what Islam encourages or permits).

Now this, on the other hand, is what I call over-reacting.