So medicine is not a science because it's concerned with what's "good" and what's "bad" for someone's health? I find this kind of argument principally flawed.

Many sciences are concerned with the consequences of human actions and it's hard if not impossible to describe these in meaningful ways without applying some criteria for what outcomes are good (desirable, positively evaluated) and what outcomes are bad (not desirable, negatively evaluated).

Besides, there is a whole area of science that maybe is more like engineering but is clearly worthwhile, too, even if it's not strictly a natural science only. For example, urban planning might not be a science in the strict sense but it's clearly important and involves scientific studies.

If policy makers can't get from climate scientist's an evaluation of the potential consequences of climate changes, then who else would produce these for them? Should they just make it up on the fly?