Mechanism design is, to a large extent, a conflict theory, because it assumes conflicts of interest between different agents, and is determining what consequences should happen to different agents, e.g. in some cases “who we should be angry at” if that’s the best available implementation.
“Conflict theory” is specifically about the meaning of speech acts. This not the general question of conflicting interests. The question of conflict vs mistake theory is fundamentally, what are we doing when we talk? Are we fighting over the exact location of a contested border, or trying to refine our compression of information to better empower us to reason about things we care about?
I would say that mechanism design is how mistake theorists respond to situations where conflict theory is relevant—i.e., where there really is a “bad guy”. Mechanism design is not about “what consequences should happen to different agents”, it’s about designing a system to achieve a goal using unaligned agents—“consequences” are just one tool in the tool box, and mechanism design (and mistake theory) is perfectly happy to use other tools as well.
There’s certainly a denotative idea in the OP which could potentially be useful. On the other hand, saying “the post has a few sentences about moral blame” seems like a serious understatement of the extent to which the OP is about who to be angry at.
The OP didn’t talk about any other possible implementations, which is part of why it smells like conflict theory. Framing it through principal-agent problems would at least have immediately suggested others.