we are criticizing how that simplified model is abused without considering the other variables and applied to policy-making. does that make sense?

That indeed makes more sense: it only fits short-run predictions. It justifies short-run policies.

Longer term policies need a different justification: you’re definitely right there.

I think economists have a name for mistaking short- & long-run effects (something to do with equilibrium), but the course was too long ago for me to recall.