Here are the official guidelines from aa.com. I think only the last point would have the potential to apply in this case. I doub't anyone would say you were unable to perform the exit row duties, but who knows. I'd use miles and guarantee the UG.
Originally Posted by aa.com
You are about to be assigned an exit seat.
Government rules require that passengers seated in an exit seat must be:
* Willing to assist in an evacuation
* Able to operate the exit door and assist others in exiting
* 15 years of age or older
You may not sit in an exit seat if you:
* Are traveling with a child under 15 years of age or another passenger who requires your care
* Lack visual capacity or require corrective aids beyond eyeglasses/contact lenses
* Require assistance beyond a hearing aid to hear and understand verbal instructions
* Are unable to understand printed emergency exit instructions or crewmember instructions
* Have a condition that might prevent you from performing evacuation functions or injure you while performing such functions