It's part of his parole. Chaim would know more about this. Chaim was also on federal parole for 5 years. Of course back then there was no Internet but he was barred from JDL activities as part of his parole. That's why he started JTF.
Pollard's lawyers will put out a statement after his release tomorrow. Just search for Pollard in Google News and there are dozens of recent articles. It's better to search in Arutz 7 because you will get Pro-Pollard articles including about how he will have his first Shabbat meal in 30 years and will eat foods he hasn't had since he was 30 years old.