Then the Assessor who assesses that Assessor should mark him down for being unnecessarily Tory !
Unless I'm mistaken(?) there are no IRB 'referee attire' insistences??
A player could wear 'multicoloured' Mitts Tights Headscarf or headguard, which I think makes boot colour irrelevant.
PS.. I recently watched a Senior Society Officer refereeing a L7 match wearing White trainers.
Take every comment from an Assessor, coach, player, spectator, barman etc with a pinch of salt; there MAY be something in what they say, or they may be biased, or unsighted, or not up to date on the Laws, or just plain wrong. Almost always the referee is closest to the situation and probably the best person to make the right decision -and normally does so.
If. however, there becomes a pattern of complaints that repeat themselves then maybe there is some truth in them. Often there is no such pattern. Referees are not perfect, but at least we are trying to be. And if no player cheated our life would be much easier.