"Out of over 9,000 staffers in the House, should we really be banning this whole IP range based on the actions of two or three? "
Tell that to voter fraud bills, the claim of "welfare queens" and not allowing female reproductive rights because "some use it to be promiscuous". Not so fun now that it's on the other foot, is it?
However, unlike those claims, they do have control of AND responsibility over their entire network. This IP ban is standard practice for IT security. If they can't secure their network, then they don't deserve access to the server. Access to servers are a privilege, not a right.