First and foremost, you should grasp the real meaning of the sentence.
Even though the detractors of who performs a flash mob says that they are not dancing. Flash mob is a sort of tricky movements without control or ungovernable (the clue word here is unruly), actually, they are wrong.
In their dancing mess, according to the detractors, there is an ORDER. which means that in their chaos, there is a clear system underlined it, even though it is not apparent.
That is the real meaning. Therefore, the word celebration is out of scope.
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