Pitcher Injured During Warmups

[wish7694]

FED rules. New pitcher is warming up between innings (started the game at shortstop). Twists ankle on warm up delivery and cannot continue as pitcher. Is taken out of game. When his turn comes up again on offense coach tries to re-enter him into the game but is told he cannot due to his leaving earlier due to injury. Coach tries to protest but it is not allowed in California High School Playoffs.

I know the rule says a player who comes into the game to pitch and cannot complete his first batter due to injury may not return as a pitcher, is their another rule I am missing that prevents him from returning to the game at all?