If I were to steelman the usefulness of the argument, I'd say the conclusion is that positions on economics shouldn't be indispensable parts of a political movement, because that makes it impossible to reason about economics and check whether that position is wrong. Which is just a specific form of the general argument against identifying with object-level beliefs*.

*For that matter, one should perhaps be careful about identifying with meta-level beliefs as well, although I don't know if that's entirely possible for a human to do, even discounting the argument that there might be conservation of tribalism. It might be possible to reduce ones' identity down to a general framework for coming up with good meta-level beliefs, and avoid object-level