Maybe they should make their government standard good enough that it wins on its own merit then. Imo, the biggest thing this block does is essentially giving the government standard a license be as subpar as they want, because it isn't like a superior non-government standard is even allowed to compete with it anyway.
Maybe when it becomes a champion on that, removing barriers of entry, protectionism, subsidies and it's public companies monopolies, then it can be a fair judge on this issue.
The Brazilian Central Bank has authority on money transfers, so whatever regulation they want to arbitrarily impose regarding this matter, they can do.
Facebook is a registered company in Brazil, they were going to operate the payments platform through a card processor, etc, so directly or indirectly they are under the authority of the Central Bank.
EDIT: by the way, regular banks and fintechs already have to be a participant in the Central Bank's payments system in order to settle funds. PIX is (also) a 24x7 implementation of the existing electronic money transfer system which only is available on working days.
Europe did the same and it worked.