There are many issues involved, making the whole claim totally, well, wrong.
The first problem is that science can't fix **goals**. Einstein explained it well in http://monthlyreview.org/2009/05/01/why-socialism but it's a much more general point admitted by most serious rationalists : science (or more exactly rationality, from which science is a subset) is the most powerful tool to understand the world, and to change it to match your goals. But science can't fix goals. It can enable you to maximize your utility function, but it can't fix your utility function. And people will disagree on goals. That's the main reason for which elections and democracy are the best (or at least, "less worse") system, for it allows people to fix the goals together. Imperfectly, but since there is no objective set of goals, no ultimate utility function, only asking to everyone what they want can solve disputes between goals.
The second problem is that science requires the ability to perform repeatable measurements. Large-scale social sciences (like macroeconomics) are therefore not really sciences. You can't perform repeatable experiments and measurements in macroeconomics, with changing one factor and letting the others stay the same. While you can measure the speed of light, or the amount of energy liberated by fusion between two given isotopes of hydrogen, you can't measure how much a tax cut or welfare policy will affect the economy as a whole. You can't make an experiment for that and have 5 other labs around the planet to repeat it in the same conditions. Same when you test a drug on humans, you'll test it on hundred or thousands of cases, comparing it with a placebo. You can't have the same level of confidence in large-scale social science (such as macroeconomics) than you can in physics or biology. You can use rationalism over the evidence we have favoring one or the other systems, but that will still be much more disputed than a claim of "science", and you'll find economists defending and opposing every proposed policy, in a way you'll never see in physics.
The third problem is that science is definitely not conservative. Associating science with conservatism is completely misunderstanding what science is about. Science is completely revolutionizing itself. Relativity and QM are the most known revolutions, but science is directly bound to the idea of **progress**, science is a process of always getting closer to the truth - making your map of reality always closer to what reality really is. Science is definitely not something static, with final answers that will never be changed. That's one of the most fundamental differences between science and religion. Conservatism is resistance to changes. Science is embracing change, realizing you were wrong and fixing it.
That said, yes, we would gain to use more rationalist (or scientific, if you prefer) approach to many topics in politics. And more trust from politicians towards scientists.
And that, I'm pretty sure, would not favor "conservative" policies. It would favor gay rights and abortion. It would oppose death penalty or gun ownership. And it would oppose the current economical orthodoxy, which just, well, fails, from Argentina to Greece to USA. Just for USA, it was much faring better off in the 60s and 70s when it add very high income taxes on the richest, and regulations like Glass-Steagall act, than nowadays after the Reagan/Bush cuts and Clinton liberalism. That part is very well open to debate, but the 3 first reasons for which those claims are just, well, *false*, are much less debatable.