Sources: Dennis Allen’s recent mishandling of Kendre Miller’s injury created internal frustration, Miller currently healthy but can’t play

Is it actually legal in NFL rules to put a none injured player on IR?
All we need is an investigation that we get punished for
The player can seek an injury settlement if they believe they will be ready to play sooner than IR would allow, and they believe getting on the field sooner is both possible and to their benefit. I don't expect it to happen here.