Updating one's unconsciously regulated social behavior is impossible in the general case, and in most of the desirable concrete cases too.

"Impossible" is a big claim. We don't put much stock in zero or one probabilities around here ...

System 1 can be programmed by System 2. There are cases of individuals updating to become (e.g.) less socially anxious; less triggered by various things; or less bigoted in various ways. About fifteen years ago I took a massive update about taking responsibility for actions that had harmed others; the details are more private than I care to post about, though. For that matter, there are religious and philosophical conversion experiences that produce dramatic social behavior change; and psychedelic experiences that do so, too.

People can change. Many people spend a lot of effort constructing rationalizations as to why they shouldn't have to, though.