IMO there's "expressing their opinions" and "trolling" and those are two different things. I agree it can be a subjective judgement call. But there's a reason that the downvote option in Steemit spells out trolling as a reason - it's anti social behaviour that ruins the Steemit community.
If someone tags their post as #science they should be ready to stick up for scrutiny as science and not run around trying to cry bully scientists that hold them to scientific principles.
That may sound "hard core" to some people but let's not forget that anti-vax propaganda is no joke, it can actually lead to people dying unnecessarily, and not even ones gullible enough to fall for it, innocent and vulnerable people who are immunocompromised.
This may be, but flagging behavior can lead to a war between the opposing sides of the argument. The flags will be returned in kind leading to obscuring of good explanations. It is best to focus on promoting good content then flagging bad content. Make good science more visible and the nutty stuff will return to the shadows. People crave factual reassuring answers. Nobody wants to live by fear driven propaganda.