This is only a utilitarian ethical argument. If people approach from a deontological perspective, the measurements may not matter.

Suggesting a policy prescription in the title of a scientific study puts the legitimacy of the study in complete question. The researchers must approach the question as one which can be falsifiable, else it's not science.

That's fine, but it should say that (and probably does; the journalism is probably the one changing the story).

If the authors were striving for objectivity, they'd skip discussion of values and interests entirely and talk solely about what effect drug policies had on certain quantifiable metrics --- all in a factual and dispassionate way.

A scientific paper is a report on the state of reality and should not contain a case for any sort of action.

It's not that the is-ought gap is unpopular: it's that the gap doesn't even make it into the debate. We're dealing with an epistemic regime in which it's acceptable to engineer desired "ought" outcomes by controlling who gets to make statements about what "is". That is, is no "is" independent from power dynamics, oppressor and oppressed. "Is", in this model, is just another form of narrative that serves the powerful.

In this world, you should expect downvotes for arguing that science informs us about objective reality, because people of a certain mindset see scientific results that contradict their worldview as just another form of oppressive discourse intended to subjugate the powerless. To them, science is just one of many equal and arbitrary forms of rhetoric and power gaming.