refuses to play with 5

[DRJ1960]

Small Private School BV. Team A is athletic, Team B seems to have mainly offensive linemen in the frontcourt. Game is blowout from the start. VERY physical game by Team B. Second Team B player collects foul #5 on an elbow to the head (my partner calls it a "T"). Coach refuses to substitute and insists on finishing the game with 4 players on the floor in spite of having eligible subs on the bench. (Approx 3 minutes left). 10.5.2 looks possible but seems aimed at a delay rather than "refusal".

What would you have done?

(Yes, the game was a "difficult" one from the tip).