I'm also defending science by, as you say, pointing out that it's like what most people do all the time. But it's precisely for this reason that I don't think that one can draw any clear distinction between scientists and non-scientists or see scientists as somehow distinct from "citizens."

Of course, we can use various terms to describe people belonging to specific institutions or working in specific disciplines, but I don't think it makes any sense to draw a general distinction between "professional scientists," "amateur scientists," and "non-scientists." (Few, I think, consider "amateur" a compliment.)