I believe scientists should keep their findings separate from their advocacy for many reasons including limiting bias in findings, and advocates like legislators would be better at advocating than a scientist.
Scientist’s works become more credible and accurate if their research and conclusions are not biased. When one advocates for themselves it creates a biased view upon the work. Automatically when choosing a topic a researcher becomes a little biased towards that subject. One cannot research the effects of air pollution on a population without stating that air pollution is bad or good. The researcher chose that subject to prove one way or the other. When the scientist adds avocation into the situation he automatically becomes more lenient towards his research results.
Secondly, I believe scientists are in the science field for a reason they are good at doing science. Communications and policy majors will be better at presenting ideas and convincing the public than a science major would. I believe scientist should stick to the research even though they might be more passionate about the subject; the advocate representative would be better at presenting and advertising the findings. They would be able to create a better policy.