I understand this. There are first year graduate students in my field that have a far deeper understanding on the basic science behind certain papers than the general public, and yet even they struggle to parse those papers' conclusions. I mean this is even true for PhDs working in the same field, given the right paper.
When I say scientific literacy, I mean something far more basic than actually understanding anything to do with any specific field. I mean (among other things) understanding what you just said, that scientific fields are deeply complex, understanding how actual science is done (peer review, incentives and motivations, author bias, etc), and, given the first two points, that one should generally be skeptical when a citation consists of only a paper's title.
> But access to source can allow someone to validate the claims by a journalist or a public officials trying to bend conclusion to support their view.
I'm aware of this, and I said that I was in favor of open access as opposed to a simply closed system (i.e. open is a, potentially quite large, net positive). I'm just pointing out that the potential for misinterpretation/misuse is also present (which is also what the comment I was responding to was pointing out), just as there is potential for validation and combating misinterpretation/misuse. But, as you said, the vast majority will be unable to read/understand specialized fields, which might lead to (potentially more frequent) misinterpretation//misuse (even unintentionally).