My own personal experience of aging is that the opposite is true. Young me thought in very black-and-white terms and knew everything. I now live in the grey and although I find it more difficult to deal with new ideas (partly because of age, partly because of the grey), I’m a lot more open to those ideas and willing to give them serious and fair consideration. YMMV, but a blanket statement that old people generally are stuck in their ways doesn’t match with my personal experience and when I think of the old people I know, to the extent that it’s true it’s true for a minority.

The referent as it relates to science probably has to do more with corruption, incentives, and careers being built on certain ideas and having pre-existing knowledge rather than anything specifically age-related.

In any case, whatever longevity treatment is applied may actually reverse or reduce whatever part of your claims have some physiological truth. It could mean more wisdom and less curmudgeonry.