Yes, those are hard coded into the constitution, but what was not hard coded was the right of any person to vote. It took a over a century for the all men (1870, 15th Amendment, but not really), and women (19th Amendment, 1920!!), and finally all people (25th Amendment in 1964!!!!!!). Each of those hard fought updates to the constitution added right to people, and we are far better for it. I have no trust that any politician, and especially the current GOP, could be trusted to sensibly walk back any rights.
People are healthier and more capable into their 70’s now then people were in their 60’s a few decades ago. In another few decades that may be true of people in their 80’s. To limit what people can and can’t do in the future based on current conditions, and to hard code it into law, is a horrible idea.