Yes, I do agree. Scientists can be advocates, and in my opinion should be advocates. In the case of clinician scientists, I believe they have a repsonsibilty to advocate on behalf of their patients. This can be interpreted in many ways, but one way for clinician scientists to advocate on behalf of their patients is to pursue research topics that could influence public policy. Given they experts in their respective fields, they are in a unique position to influence health policy and healthcare policy by identifying gaps in care and social equity, and providing empiric data to support policies for the public good. In an ideal world, rigorous scientific data would inform all public policy but sadly this is not the case.
The best way to balance advocacy with objectivity is to perform rigorous scientific inquiry. The study design should take priority over the potential policy implications and whichever side of the policy the scientist falls on. While, scientific inquiry can rarely be 100% free from subjective bias as no human is 100% free from bias, rigorous methods can maximize the objectivity of the study. Even if bias occurs in the interpretation of data, the raw data should be objective. For scientists who take on an advocacy role where they are attempting to influence policy, the research must take a front seat to the advocacy. They must be truthful in their interpretation of the data as it applies to the policy at hand. All that said, I think clinician scientists make great advocates if they can remember that first and foremost, they are scientists.