In this message, the proportional solution is dropped in and the result is checked. Ending iterating too soon increases the proportionality of the solution but has it fail to comply with the axioms.
Maximal proportionality is an axiom.
The technique seems to be unable to lead to an error. So it seems safe to stop iterating without checking that the iterating has stabilised. Even it is had, the bounds could be too weak. The solution to VBC is, according to P2, given by renaming ab' with ab, and ac' with ac. And the preferential voting theory is solved for the 3 candidate 1 winner problem.