I’m not sure where you got the idea that people are afraid of non-scientific ideas–I see them discussed all over online everyday by thousands and thousands of people. No one is afraid of them, we just don’t consider them to be science. There should always remain a sharp dividing line between non-scientific/scientific and for good reason.
That is a patronizing statement. If science can't defend itself then we're more screwed than we thought. Truth exists outside of Science (to state otherwise would not be a scientific statement, thus a contradiction). That leaves room for crack pot theories to potentially have truth in them. To bar them or dismiss them based off personal bias is crime against healthy intellectual discourse. Who is imposing irrational beliefs on whom? That is where the sharp dividing line should be drawn.
I'm also afraid of the measurable societal harms caused by, e.g. the anti-vax movement, where preventable illnesses are making a comeback due to non-scientific belief in the hazards of vaccination.
I don't know how to get anti-vax sentiments out of the mainstream discourse, but I think the world would not be any less intellectually rich, in any meaningful sense of the concept, if no one ever thought those thoughts, and caused harmful policies to be carried out, again.
Right now, of course, I accept it as "gotta take the bad with the good" but that doesn't mean I like that things like childhood measles are on the rise in various anti-vax hotspots; especially because these aren't informed adults opting out of vaccines, but ill-informed parents making decisions for their children that do have serious impacts on childhood health and the potential for serious harms later in life.
I certainly don't see the need to defend some ideas as holding promise for progress ("we could have cured your measles as a child, but some guy made up a story out of his head and that's why you have shingles now") when they are very much regressive ideas.