I'm not sure why you think this is a slam dunk. Fruity flavors increase the adoption of vaping because it tastes better, but that doesn't work when you apply it to broccoli. Doesn't mean we shouldn't regulate flavored vapes.
Vaping analogy is not perfect, as it doesn’t hold true in some aspects, but... Nobody makes vapes that go unpleasantly sour for a while after a fourth puff. But if they do we’d better not ban them from adding flavors, when the flavoring here does the right thing.
We’d still want to regulate vaping on other aspects (such as harm to health, which - unlike speech - doesn’t get protections), but that’s another, different story.