There are various accounts on Twitter which were being investigated etc. for criminal misconduct, Twitter was given a court order to block those accounts. I have no idea if that order was itself justified (IANAL and I don't speak Brazilian) but the orders were given by someone with authority to give them.
Twitter refused the order, which means that Twitter is interfering with the legal process in Brazil. This sounds like "contempt of court" to me, which is a thing which results in a judge sending people to prison — no idea what it is in Brazil, but IIRC the maximum penalty in my country of birth is 2 years' imprisonment.
Brazil's legal system requires companies like Twitter to have an office in the country in order to receive such orders, which I think means it's literally her job to make those orders happen. Regardless, by closing the office Twitter was directly violating Brazilian law.
As companies cannot themselves be imprisoned, I do not see what alternative there would be than directing obligations onto a specific human. Buck has to stop somewhere, and while I know a lot of people who would celebrate if this judge decided that the correct somewhere was "international arrest warrant/request extradition of Elon Musk personally", I suspect this judge would have to go through a few more checkboxes before that doesn't get "major diplomatic incident" written all over it.
(Perhaps less of an incident if it's concurrent with the EU saying "We're issuing Twitter with a 6% fine on their global annual turnover for non-compliance with the Digital Services Act", which seems to be another battle Musk is Leeroy-Jenkins-ing himself into).