The point is that in both cases people are complaining about a conceptual reduction which they don't recognize because the resulting vocabulary doesn't happen to resemble the everyday vocabulary.
Thinking that decision theory lies in a separate magisterium from social pressures is, like most compartmentalizations, a failure to properly abstract. It's akin to not realizing that the physical theory of work includes forces being applied through distances within the body of an organism, and that part of the whole point of a physical theory is that it should not explicitly invoke complex higher-level notions of psychology.
It seems to me that usually, when someone says "ethics" on lesswrong, ey usually means something along the lines of decision theory. When an average person says "ethics", ey is usually referring to a system of intuitions and social pressures designed to influence the behavior of members of a group. I think that a lot of the disagreement regarding ethics (i.e. consequentialism vs deontology) is rooted in a failure to properly distinguish between decision theory and what society pressures people to do. Most lesswrong users probably understand the distinction fairly clearly, but we only ever talk about decision theory. Why don't we talk about the social meaning of ethics?