You provided several links (many of which were not relevant) that support the idea that a portion of the population (not the whole of a population) believes something. I am having a hard time figuring out why you are unable to differentiate a % of something from the whole of something.
Am I making an assumption when I think the general public associates red baseball caps with MAGA Trumpers? No, because that’s one of their symbols.
Again, you are doing the same thing, so I guess you're consistent. I associate "MAGA" hats with Trumpers, sure... but my initial inclination when I see a red hat from afar is that it's a baseball cap (maybe Angles, Cards, Reds...). Once again, I am a portion of the "general public" that you're completely ignoring; and in doing such, you make a logical fallacy.
“General population” is typically in reference to prison populations; but the term can be used when referencing a full sample size, E.G. 70% of the general population associates red caps with MAGA.