In part your question feeds off of gullibility. When it comes to that, I am just as gullible as you are.

I am quite concerned over the continued vilification of all Muslims - throughout the western world, but especially the US. I believe that this may be a precursor of worse things to come.

We are for Justice and Mercy, and Truth and Peace, and true Freedom. Edward Burroughs 1659

first off, urban legends are carefully crafted brainworms -- ideas so irritating or intriguing or salacious that they tend to fascinate us, juicy gossip tidbits that cry out for repetition, that make a good shock-value anecdote.

second, human behaviour over the millennia is in many instances so bizarre,  often so outrageously abusive, so absurd, so unfair, often grotesquely sadistic and violent, that it's hard at first glance to dismiss any nasty allegation about cultural vagaries or religious dogma as prima facie ridiculous.  who would give credence to the nastiness of (to pick just one ghastly example) FGM if it were not well-attested and documented?  or (historical) footbinding?  or the trade in prostituted children, including the "Asian sex tourism" so popular among highly respectable affluent Amero/Euro corporate drones?

so it's not prima facie absurd that some patriarchal religion or other could have a fine-print commandment that certain kinds of sex with children are OK for adult males, but others are not.   in fact it's pretty believable in the long historical context of male sexual entitlement and the lowly status of women and children.

but right now, in the islamophobic atmosphere of US propaganda, it's a bit of meme-warfare masquerading as "human wickedness as usual".

antisemites used to accuse European Jewry of killing and eating Christian babies...  the Blood Libel as a concept never dies, the ascription to the loathed Other of the full depth of human nastiness that each society wants to pretend could never occur w/in its own ranks...

The difference between theory and practise in practise ...