Big mistake.

In a situation like that, the best thing to do is to do exactly as they tell you, observe as many details as you can about the situation and fight it another day.

Other than that, I saw nothing wrong

Now, like was pointed out above, they had better have a damn good reason for doing what they did (i.e. names, witnesses to a specific event, hard evidence, etc.).

The word of an anonymous aggrieved imam over some group proselytizing in Dearborn doesn't cut it.

One thing I am curious about in this case: Given that the ACLU is aware of the situation, have they pledged to assist in the case in any way?