The clothing is not sacred attire. This is NOT the equivalent of dressing as a priest in robes or a Friar or whatever any other religion uses for sacred rituals or ceremonies. This is NOT the equivalent of the low class Yewt fans using sacrament trays and cups to drink shots. This is NOT the equivalent of the low class Yewt players performing "baptisms" in a hot tub or training pool.

Those are examples of things done by supporters of the opposition that "could" be offensive.

Everyone of these kids probably already has a bike helmet and a backpack. most probably even have a white shirt and a tie. Just putting on clothes that people normally wear is not offensive.