In principle I agree with Ivan. If someone doesn't have scientific training, then their scientific opinion is of very limited value. They don't just hand out PhDs, as those of us in grad school are well-aware.
But I'm troubled by your phrase "difficult to prove." If a theory is difficult to prove, then it's not really a theory, is it? Scientific theories have to be testable and falsifiable. They aren't "proven" in the mathematical sense. But an idea has to have a good deal of scientific data in support of it before it can be called a theory. And if a scientific hypothesis is resting on shaky ground, then I wonder why we are allowing it to have such significant global impact. If we weren't sure about the effect of a certain vaccine, would we want to supply it to the public? If we weren't able to place definite constraints on the mass of the Higgs' Boson, would we want to spend billions of dollars on a collider that will operate in the appropriate energy regime? Certainly not! Scientific theories have to have a solid backbone in order to be afforded that label. So if a theory rests on shaky ground, then it seems to me that it's the responsibility of us as scientists, and not the general public, to voice concern.