I think it is very hypocritical for the government to hack a hacker to bring them to justice. There are other methods they could have used to catch this person, such as tracing their activities online. The government should try, at all costs, to follow its own rules it has placed against society, hacking included.
The U.S. is not wrong for hacking into the accounts of a known cybercriminal. However, to do so it must have probable cause to believe the cybercriminal has committed a crime and secured a warrant to search the account. We are a nation of laws. Even criminals are guaranteed that protection.
If the U.S. government sees a known cybercriminal and is able to hack into his/her accounts, they should. Cybercriminals are some of the most dangerous people in the world because they often enable other types of criminals to have advantages. Cyber security is a field that still has a lot of work yet to do to make it safe for everyone, and we must do what we can on the forefront of it.
In order to catch their most wanted cybercriminal, the United States government had to do a bit of hacking of their own. They accessed his personal information, which allowed them to figure out his embarrassingly weak password. I think that the U.S. was right to act this way. They had to think like a criminal - if they hadn't, this hacker would still be on the loose.