Ethical projectivism isn't quite so much a theory of mind as it is a theory of ethical language. It's clear that in most cases where people say, "X is wrong" they ascribe the objective quality "wrongness" to X. Projectivism holds that there is no such objective quality, thus, the property of wrongness is in the mind, but it doesn't feel like it, much like how the concepts of beauty and disgust are in the mind, but don't feel like it. You can't smell something disgusting and say, "Well, that's just my opinion, that's not really a property of the smell;" it still smells disgusting. Thus, projectivism has the same rejection of objective morality as emotivism does, but it describes how we actually think and speak much better than emotivism does.

The attack on emotivism as not accurately expressing what we mean is largely orthogonal to realism vs. subjectivism. Just because we speak about objective moral principles as if they exist does not mean they actually exist, anymore than speaking about the Flying Spaghetti Monster as if it existed conjures it into existence. But the view that moral statements actually express mere approval or disapproval seems clearly wrong; that's just not what people mean when they talk about morality.