I know men 10 years his junior who struggle to get up the stairs at night.
He's already beyond the average life expectancy of a man of his age; so he has a few cranky ideas about his cereal – perhaps you should consider how incredible he still is, physically at that age and how your own parents / grandparents were / are at 80 and bring that into the equation before shooting him down in flames.
1/3rd of the UK’s population have some form of dementia from their 60’s onwards – my God, If I could still attract a woman like that even now, at 46, I’d die with a smile on my face and a box of frogs on my cereal every morning if needs be!