>>Merely starting the interview process with someone who far exceeds the requirements for the role is a risk... my employees and I may waste our time interviewing this person just to find out their salary requirements are too high. I would say "too experienced" is a legitimate reason to reject someone from a role for this reason.
I'm pretty sure this kind of thinking is exactly the problem and accurately describes ageism. You've made assumptions about someone based on their age and don't even want to bother interviewing them based on stereotypes that you think are true about older people. Of course, there are extremes to the "too experienced" situation. If a person with a Ph.D in Biology and Astrophysics applies to a job at McDonald's, then perhaps something is off. But you should still talk to the person and find out what's going on; not just assume.