I don't see this as a partisan issue at all. I don't think there should be any "jobs" you are guaranteed until you die. It is hard getting old, but skill sets do change as you do. I notice this already and I'm only in my 50's. For example, singing voice, I notice changes in mine. If I had been singing the national anthem at an event should I be allowed to continue until I die despite changes in my voice? (Can you imagine how painful that would be?)
It may not have been handled as judiciously as it should have been, but I don't get how he should have the "honor" until his death regardless. He was chosen for a skill set. It that skill set is no longer the same then it is time to replace him. I think inviting him as a special guest makes sense. My parents are in their 80's and, although they are certainly capable of reading announcements, there is no way they would be able to do the same job they would have a few decades ago. My mom still plays the organ at church and is much appreciated for what she does, but there's no way she'd play at a national event that the whole world was watching.