I'm sorry for your brother's situation, but the law is clear on this. If his FMLA has been exhausted, then his employer may legally require terminate his employment if he is unable to return to work. Ohio does not have any state law that extends his protected medical leave. Unless he has a legally binding and enforceable contract or CBA that expressly gives him more time, 12 weeks is the maximum he is entitled to.

My best to your brother and good wishing for continued healing.