Unfolding a claim doesn’t just serve to provide justification, it also opens the claim to better attacks. It sets you up for (good) defeat; Unfolding involves sharing understanding, so that more understanding is put to the test (ref).
Even if the justification isn’t the best argument for the claim, it would be representative of current understanding. Keeping claims folded makes it harder to develop understanding of them.
What does unfolding a claim look like? It can be anything from laying out a proof to gesturing towards your reasons for belief. The important part is putting more out there to be wrong about.