The problem with your theory is the only way they could get his ISP information would be from Jim since ISP information isn't posted anywhere.
I'm a mod on another board which is owned by my son. ISP's are logged but can only be seen by those with admin capacities. The only reason we need to have that information is in the event we need to ban by ISP someone who trolls excessively or posts certain banned pictures.
I have NOT read the previous 300 messages, but if Jim ever posted a picture in here and referenced a pic from his own machine by IP or better yet domain name they could have found out that way. But that assumes that he is running his own domain server and it's registered with ARIN under his own name.
The problem with your theory is the only way they could get his ISP information would be from Jim since ISP information isn't posted anywhere.
I'm a mod on another board which is owned by my son. ISP's are logged but can only be seen by those with admin capacities. The only reason we need to have that information is in the event we need to ban by ISP someone who trolls excessively or posts certain banned pictures.