Because he was putting people's names in message walls, without any helpful content, and it has been done by users whose IPv4 address starting with 101.182 or with their IPv6 address starting with 2001:8003:4EDB:E200.
In this case, his IPv4 address started with 101.182, so he was included in the group, thus we assumed he had some sort of connection with the other vandals. And because mass vandalism is not allowed, his block is infinite.
Heads-up: Your IPv4 address starts with 101.182, so I'll keep an eye out on you. Even if you are not part of the "group", you will still be banned if you do something bad. But just don't do any bad things by breaking rules in Guidelines and you will be fine. :)