We have a guy on my sons JV Football team whose younger brother was diagnosed with a rare form of cancer a couple of days before school started. He was wearing a yellow "life" braclet during last weeks game that he forgot to remove before the game started. Instead of telling the kid, or the coach, to remove the bracelet, the Ref gave him an "unsportsman like" penalty. You know "rules are rules".
Players have been told those bracelets are illegal from the beginning of the season. The coach is asked before each game if his players are in the proper uniform. Refs routinely go amongst the players before the game to inspect. The player knew it was banned. Proper penalty!
But the referee has the right to give that penalty on the coach. It is the head coaches responsibilty that his kids are legally equipped. The umpire and referee verify this before each game.