Web sites themselves manipulate search results to appear higher in the results than they might seem to merit, so a naive presentation algorithm is also "manipulated". Any ordering represents somebody's opinion on what you should get back; there is no single universal objective search result order.

I have no idea if Google is specifically pushing vaccine denier sites down the list, though I can say that the entire concept has far more "mind share" than the notion merits scientifically. That much, at least, is objectively true.