As much as we talk about securing your systems, having someone in-house go rogue like this is a MUCH higher risk to your data than having someone break in. Internal unrest (or stupidity) will probably bite you harder than crackers will.
The reality is that organizations have to be able to deal with both internal and external threats, and a lot of the effort on that front has been around reclassifying access to no longer consider insiders as trusted (which an argument could be made that they never should have been trusted to begin with).
‡ http://www.verizonbusiness.com/resources/reports/rp_data-bre...