Depending on what was hacked. Anonymous on occasion challenged the notion of "activism" and indirectly endangered human lives. The mastercard hack would have been quiet scary for people whose, on the day, lives depended on their card.
Does that make them terrorists? No. It does place them into the exact gray area that they decided to act in, they are neither activist nor terrorist: rather something in-between.
Does that justify putting Jeremy on the watchlist? Just like his actions, it's a gray area, there is no good answer.
There is no right or wrong here, nor does there have to be. Anonymous's actions were often ignorant and dangerous: don't make yourself the same by blindly defending everything that they did. These are difficult questions, spend more time thinking about them before trying to answer them.
This person has no respect for government, and maliciously and repeatedly breaks laws put in place to protect the citizens.
Terrorism literally means to cause terror. People get pretty terrified when people steal and abuse all of their information.
Also, hacking can and does cause death. Consider what happens if you hack into the computers at a drugstore and change the prescriptions to give people the wrong drugs. Terrorism?
If he only causes economic harm, I could be convinced that he can still be guilty of: destruction of property, computer fraud and perhaps sabotage. But terrorism?
So hacking is equivalent to murdering people via bombs? Are protests that disrupt traffic also terrorism?