No Country for Old Representatives?

I am not a fan of term limits. I will often strongly argue against them. As a voter, I feel it is my duty to determine if my representatives at various levels of government are still worthy of my support, not some arbitrary number in a law.
I do understand the sentiment behind term limits. Inertia and the power of the incumbency are powerful forces to overcome. There are better ways to go about it other than arbitrary limits.
Unfortunately, the argument for the past few years has become relatively stale; neither side able to agree on a way to reform the way we represent ourselves in our government. You can imagine my surprise when I stumbled upon a very thought provoking idea in the cesspool that Twitter has become:

An arguably arbitrary number to be sure, but this one does make a bit of sense. In the late 1780's, life expectancy for males was in the area of 38 years. The multiple wars fought by our infant nation in the years that followed cut into that a fair amount, but it is still significantly less than it is today. The Founding Fathers, despite many of them living quite long lives, couldn't really conceive the idea of an 85 year old politician who may or may not be in total control of his faculties still serving in government. They set lower limits (25 for House seats, 30 for Senate and 35 for the President) presumably to require a certain maturity amongst the Congress and presidency. Had they been able to forsee the possibility of the above example, I feel confident that they would have set upper limits as well.

Where do you draw the line? It still is putting an arbitrary number on people. Let's use my retiring Congressman, Jim Sensenbrenner (R WI-5) as an example. He is retiring at the age of 77. In this past congressional session, he sponsored 17 bills, co-sponsored nearly one hundred more, and pre Covid, would hold dozens of in person Town Halls throughout the district during every recess period. He engages with and listens to his constituents constantly. Another example would be my senior Senator, Ron Johnson (R WI). At 65, he is not only standing up for Wisconsin residents, but American citizens as a whole. He has been a champion against waste and incompetence in government for years.

Both examples show that 65 is too young an age to draw a line. 70 probably is too. Old doesn't always mean feeble. At 71, Bill Pascrell (D NJ-9) was instrumental in getting the ConTACT Act (relating to sports related brain injury) passed in 2008. Are there elderly members of Congress that are back benchers? Sure there are. There are also plenty of young back benchers as well. When our junior Senator Tammy Baldwin's (D WI) greatest claim to fame is saving the cheese boards for the cheese making industry, you have to wonder if the 58 year old is really giving it the ol' college try.

In the end, an age limit for Congress is still an arbitrary line that has little bearing on how well a person can represent their constituents. However, that just might be the compromise to generate new, meaningful discussions on the subject of how long is too long in public service. I'm still against zero tolerance lines, but I'm at least willing to explore this possibility with an open mind.