How is one to refine their expectations of other people's abilities, if not by updating on available evidence?

Pot, kettle, incidentally. Compare parent's "I immediately lose a bit of respect" with your "you're an absolutist who [...]" The latter makes a much broader claim based on a similarly small piece of information.

You should work on your reading comprehension since I did nor said no such thing. Losing "a bit of respect" is not equivalent to summing someone up by a single opinion, it's not even close.

I don't get it. Are you arguing that one should not be able to adjust their respect for a person based on that person's political leanings and/or lack of literary taste?