Doesn’t that suggest professional ethics are immoral? They block a temporary, one off experiment which could suggest how to avoid sadness.

The alternative is relying on intuition only and possibly making people permanently sadder. Or is there a way to achieve this knowledge consistent with the field of research ethics?

We saw this with challenge trials in the pandemic where ethicists fretted people would reject them and concluded challenge trials are immoral. Meanwhile opinion polls suggest people view challenge trials as virtuous and the current method of waiting for infections as immoral.