What people mean when they say that is that someone's opinion on evidence-based policies shouldn't be intertwined with their allegiance to a particular party. The entire point of politics is determining policy, and policy has an effect on the outcomes the doctors that wrote the article want to improve.
In any case authors are clearly making a political argument and implying if not explicitly making a causation argument here, not merely describing the state of the world.
The state of the world is the result of politics. You can't talk about one without talking about the other. Like the Texas energy grid being a disaster is the result of conservative deregulation and privatization. Merely describing the state means you're simply describing the effect and not the cause.
