I don't know. I don't mind people taking a stab at it, but it should still be looked at skeptically, especially once you move away from measurable metrics as it ceases to be science.

The subjectivity of experience doesn't prevent something being science.

How might someone conduct a blinded placebo controlled trial of a suicide prevention campaign, or of parental advice to help reduce risk of cot death, for example?

They wouldn't. They'd roll up their sleeves and get deeply involved in the messy, unpredictable world of human emotion and social interaction.

And that's good and appropriate, and there are effective and responsible methods for doing it.

Just because we can point to something and say "aha, that's subjective" doesn't mean we need to eliminate it. In fact, the more we try to eliminate it, the harder it becomes to translate evidence from the lab to the real world.

Objectivity world be nice, but it's vanishingly rare.