Doesn’t he have a reason to not render assistance? Richardson and others have taken refuge in the infirmary, but are presumably still in the middle of a prison riot. Couldn’t they reasonably fear for their own safety if they were to provide aid to the injured guard and they were found by rioting prisoners? Other guards who have taken refuge would be in no more danger than they were before but other prisoners could fear retribution from rioters. Richardson could also be inviting retribution on not only himself but the other prisoners in the infirmary if discovered.
He should try to help and he may regret not helping later in life, but I agree with others that there is no legal or licensing issues for not helping. It is a riot.