It's what they do tho'... brainwash a new generation to recite the filthy book of intolerance without any critical analysis. Once you hear "Maktub" (it is written!) all further discussion normally ends.
Why 'alarm bells'? He was filthy. And he was old. Filthy old men should not be 'teaching' young girls. It was quite evident from what I saw, this imam had absolute power over those girls. The expression on their faces was boredom, fear and disgust.
The potential for more than emotional abuse did not escape me. Is that what you meant?