It's better that scientists be clear about context when communicating. There's nothing wrong with a single person being both a scientist and a political advocate. But they ought to be clear which hat they're wearing at any given time. Science is a process that can never give definitive guidance on public policy.

Medicine is extremely complex and medical errors are the 4th leading cause of death in the US. The science on the next steps of treatment is often incomplete, variable, and dependent on the practitioners' experience. You shouldn't simply trust your doctor, but instead get a second opinion at minimum, and probably a third and fourth if you're able. It's best to triangulate on the problem, searching out varying perspectives from subject matter experts, listening to how they disagree, in order to better understand reality.

The point is more that "the science" is too broad and vague and uncertain. The science for cancer might be that the currently best known treatment acknowledged in country X is to follow a particular treatment process. That changes across time and countries. And often the studies have assumptions baked in. So there isn't a blind belief in "the science"

ideally, science would be the best available information on "is". When the science is i.e. funded by a tobacco company and regarding the safety of tobacco, we should be skeptical. How much of current science falls in a similar class?