This is actually way more serious than just abandoning her post:

The agent and her family members bypassed the Uniformed Division checkpoint and were escorted by an unpinned event staff into the room to breastfeed, the sources said. Unpinned means they have not been cleared by the Secret Service to be there.

So we have:

• an abandoned post
• a bypassed checkpoint
• two family members inside the security perimeter
• one member of the event staff uncleared to be where they were

Stop messing about, some people need to be charged with treason right the fuck now. Lets start with the agent abandoning her post and the people at the security checkpoint.