I'm curious what you base this on.

No doubt that DHS/TSA IT system administrators monitor DHS/TSA computer network systems to ensure compliance with appropriate federal regulations and policies such as making sure no one uses government computers to access pornography; that they're used for official use only; that SSI is not compromised; etc. And this is pretty standard stuff.

However, if you're suggesting that DHS pays contractors to intercept private computer networks and/or monitor DHS employees who access certain sites outside of duty hours, then please offer some reliable sources.