And this, dear reader is the crux of the problem. Are you honestly trying to tell me that Celtic don't have a problem with sectarian bigotry as well?
Celtic were effectively a movement borne out oppression from anti-catholic sectarianism. They're champions of the oppressed! They carry Palestinian flags to their games in recognition of those poor sods evicted from their homes. Any aggression coming from celtic is a reaction to the constant goading far the 'bigoted' Rangers.