You are committing fundamental attribution error if you think people are coherently "consequentialist" or coherently "not consequentialist", just like it's FAE to think people are coherently "honest" / "not honest" etc.

This is false.

The FAE is to attribute someone's actions to a trait of character when they are actually caused by situational factors. This does not imply that it's always an error to posit traits of character.

ETA: it still might be the case that there are no consistent habits of action, in which case it would always be a case of the FAE to attribute actions to habits, but I think the burden of proof is on you for denying habits.