It's a tough one, after all, sys admins have access to every file on their networks.
If they didn't check the files (remember these are checking files flagged up by automated systems), then it would be impossible to ever get rid of the stuff or ban users. Either that or the just delete every file automatically flagged up by the scanning software.
It's a bit of a tough call, and I wouldn't like to make it.
Biting the hand that feeds IT
