WhatsApp provides a service in a country, they gain direct financial benefit from almost 100M users, they received a subpoena and ignored it because it's Brazil, if this would've been a European nation they would most likely have complied, if it were a US court order they would for sure have complied.
The only "might makes right" here is WhatsApp ignoring the subpoena because they are an almighty multi billion dollar US company which thinks it's above the law. And on the other side we know that there's pretty much no company on the planet that would dare to defy a US subpoena or court order.
Should only US and "western" nation's legal systems be respected? Is this some how morally compelling to you?