Exactly what I said before. Brazil took advantage of Argentina's stupidity
The only defence I might make is I read, not sure if true, there is some allowance for football matches but not sure if true
There is indeed a specific agreement across Conmebol countries and their health authorities but it relates to continental competitions and bubbles that travel within the region. Players having been in UK, South Africa or India is clearly a rarity, a Brazil-specific exception to the rule that nobody would have even noticed if it weren't for how it became public knowledge that no Brazilians were accepting call-ups and the Argies instead posted pics all over social media showing how they were real patriots. It's a very public breach, I imagine Twitter in Brazil was full of people complaining about all this.
The Brazilian federal police showed up at Argentina's hotel way before the game to deport the guys. They of course didn't submit to their demands.
After much coming and going (with Conmebol intervening) the authorities stepped down on the basis that since they were already in the country they could stay in the hotel and quarantine there. Technically, that was an elegant solution, except that they didin't quarantine and showed up hours later on a football pitch, easy to identify given their names are plastered on their backs.
It's pretty clear Conmebol were privy to the issue and Argentina effectively were given the OK. So much so that the Conmebol statement specifically alludes to the ref suspending (not the walkout) and how all that matters in FIFA/CONMEBOL competitions are THEIR rules. I.e. Argentina won't lose the points here.
Can you make the Brazilian NT lose their points because the Brazilian health authorities act according to the law when some suits at Conmebol think they are above it? No, you can't really.
My guess is they will strip Brazil from playing home (backlash with unruly authorities that won't submit to these all-powerful beings that run football) and re-schedule at a later date (possibly even a money-spinner in Qatar for all they care), by which time both will be qualified and either side will walk out of that nuisance.