The schools did teach about other religions. Ofsted's quibble with Park View was that from year 9 onwards, R.E was overly focused on Islam, ignoring that from year 9 onwards, RE is a completely optional subject anyway.
More importantly, there is no evidence that the schools encouraged intolerance.
This is the problem when people start bandying words like extremism around, things start to get twisted to fit the "facts".
I think Icimoi's post upthread here is probably the best summation of what occurred
"I heard an interesting comment on the radio to the effect that a number of these schools are in pretty rough areas, and the emphasis on religion has been a reaction to that: parents support this because they hope that, if their children are encouraged to adhere to Muslim values, they will have a strong sense of morality imbued in them and be deterred from joining gangs, experimenting with drugs, and getting led astray generally."
Salma Yaqoob on Question Time last night said that if these schools had been in leafy areas, this would be seen more as an issue of "pushy parents", rather then extremism.
Frequently we hear about the difficulties children face because parents aren't interested or engaged in their education.
These parents were interested and were engaged. It's possible that they were too pushy, too influential and that there were problems with governance. That could have been rectified, guidelines asserted and clear boundaries being delineated.
Instead these parents have been told that they are failing their children and their morals and values are insufficient, so their children need to be taught new ones. I think that the message this sends out to these parents and children is nothing short of disastrous.