Even in a "normal" world without quarantine, there is not a hope in hell any of the European based South American players would have been able to play games on Saturday anyway.
Argentina kick off at 00:30 and Brazil kick off at 01:30 tomorrow morning. The players wouldn't be physically back in the country until at least Friday night and their sleep patterns will be on an entirely different continent.
How FIFA can think this is right, I will never know. The football season is going to descend into a farce over the next couple of years.