They’re saying that politicians like AOC, Katie Porter, Sanders, etc. are high quality public servants, and that high quality public servants should be able to be elected as long as they have cognitive function.
On one hand, in a hypothetical and ideal scenario, that would be nice to have for us voters.
On the other hand, even if an elected official does great work and has a great track record, should they be able to just serve indefinitely until their brain gives out? There’d be a lot of potential problems such as having entrenched and corruptible political operators, even if they started out good, who prevent “fresh blood” from entering politics. It’d be neat to see a study comparing different countries and political systems where there are age barriers and term limits vs those that don’t have them.
I think that’s their point: That maybe, as long as a candidate is mentally fit, then voters ought to be able to continue voting for them if they feel like the candidate is still worth voting for.
Honestly, if there was some kind of magical bullet to simply ban candidates who are mentally unfit (i.e. losing their marbles) from holding office that couldn’t be exploited, I think a lot of people would find that preferable to an age limit.
That doesn’t address issues like politicians who are too technologically illiterate to do things like open PDF files, though.