Earlier quoted context omitted.
But its not a lawful subpoena. What's app is a America n company, so it should only respond to American supoenas. Just as a American judge should not be able to order a Brazilian company to do anything before having it go though the Brazilian courts.
A Brazilian company with a presence in the US could absolutely be subject to a US court order without any court in Brazil needing to be involved. You don't get to dodge the laws of a country you're operating in just because your HQ is in some other country.
Just because they have users there is not the same as a business presence.