sports dont tell coaches how bad they are hurting, listen to interview after interview with players who talk about hiding concussion symptoms from coaches as just one example. Lots of guys have so much desire that they dont want to come off the field - whether that be because they are not confident in their backup, are just so competitive that they want to help their team or are just afraid of a Wally Pipp situation.
Beyond that, we aren't necessarily aware of all the details of what is and was communicated.
Who knows whether it would have made a difference if Riley played or not, but I'm not going to blame him for trying to gut it out.....if a coach doesnt bench a guy due to poor performance and the medical staff doesnt sit him down due to injury I just think it is unrealistic to take yourself out.