In most places, citizens below a certain age can't vote, yet laws affect them as well. By extension, one could probably argue that some people "don't know what's best for them" and experts/educated people are better suited to make the laws.
(However, creating such a test would obviously be impossible in practice, and would result in a conflict of interest, leading to discrimination, as muusemuuse points out.)
Many MAGA/libertarian/fascists love ice cream. Does that mean ice cream is bad? We should be able to make up our own minds about things instead of turning everything into a partisan issue. A broken clock is right twice a day.