All subdomains aren't exactly all trusted. The only one that I use is freedns.afraid.org
Maybe they were some source of illegal activities, such as spam sources, and domains for posting up illegal / phishing web sites.
Most websites, which are free, tend to not have regulations for subscriptions of the domains - they don't have the verification procedures, that godaddy has, for example.
I guess that's why it got suspended.
Read "Co.cc Domain Service Fees" carefully.
.co.cc is free (2 domains) for one year only, after that, it need renewal fee.
Also, it's not free for .co.cc bulk domain registration it cost $10 for 100 domains and up to $1,000 for
it was obvious that in the months prior
I guess maybe caused of violation usage of it.
They were suspended due to too much spam sites on them