Maintenance people (whether it's janitors or sysadmins) need more access than the average staff member. There's probably a lot that he didn't really understand in any great detail, but I can certainly imagining him being in a position where he saw a huge amount.

Sysadmins know a lot. They run the email servers. They configure hardware for a number of projects. They set up the databases. They see everything that breaks (and in software, that's everything). There's probably a lot of control over the actual data, but the basic workflow is something that would be very hard to hide from the people who are keeping the systems running.