I don't contend that the DoE or any other agency has a right to privacy from Brazil. Spy craft is just a part of international politics, turnabout is fair play.
Do you think it's bad if the U.S. prosecutes Brazilian spies who spy on U.S. organizations? Shouldn't we care whether the things that the justice system is punishing people for are things that are actually good or bad? (I mean, I guess your intuition probably says "no, not really"!)
I think if it's wrong we shouldn't do it (because we shouldn't do things that are wrong), and if it's not wrong we shouldn't punish other people for doing it (because we shouldn't punish people for doing things that are not wrong). Yes, this is exactly attempting to apply personal morality to the "international system". Which is made up of people who make conscious decisions about how to behave toward other people.
I think lying/misrepresenting is bad and very harmful, however I also think it is human nature, and spying helps to alleviate that information asymmetry.
I think if it's wrong we shouldn't do it (because we shouldn't do things that are wrong), and if it's not wrong we shouldn't punish other people for doing it (because we shouldn't punish people for doing things that are not wrong). Yes, this is exactly attempting to apply personal morality to the "international system". Which is made up of people who make conscious decisions about how to behave toward other people.