A popular saying amongst boomers in the late ‘60s & early ‘70’s was “never trust anyone over 30”.
It was more of a thing that was supposed to have been said, but never really was and too stupid to be believed.
I was there. It was a “thing” (even though we didn’t have “things” back then). I heard it many times. I even said it. It was meant to be ironic — very ironic. Either that, or too stupid to be believed. I’m going with irony.