It's not that simple: it seems that the issue isn't that WhatsApp/Facebook have wilfully disregarded the subpoena, but rather that Brazil isn't happy with their assertions that the information requested doesn't exist. WhatsApp has previously stated publicly that they don't retain any messages once they're delivered; if this is true, it's not strictly that they aren't willing to comply (though this may also be true), it's that they can't comply.
I agree, and if they CAN'T comply, they should address it on the court, not on a public statement that has no valid legal value.
That's what it comes to. The court requested three times, increasing the fines each of the tries and it was received with [legal] silence from Facebook. That's why they went ahead and issued the arrest warrant.
The odd thing is, there are so many ways you can avoid an arrest legally in Brazil as long you have the legal resources. They could have thrown a liminar (injunction?) to avoid handing the data or, as a last resort, an habeas corpus to avoid the arrest.
Our ex-president Lula has just avoided questioning/testifying on a corruption case. He's suspected of having gotten an apartment from construction companies as a bribe. It was on someone else's name, so he doesn't pay taxes on it etc (also illegal apart from the bribe). This is much more serious than this Facebook case, and there's so much evidence now that it would be a slam dunk case in any decent country. And Lula got out of it legally.