For site security purposes and to ensure that this Web service remains available to all users, this Government computer system employs software programs that monitor network traffic to identify unauthorized attempts to upload or change information,. Anyone using this system expressly consents to such monitoring and is advised that if such monitoring reveals evidence of possible abuse or criminal activity, such evidence may be provided to appropriate law enforcement officials."
The security header that you have posted DOES NOT restrict use of the computer system...it does however warn that tempering with the computer system or altering any of its contents is unlawful.
Knowledge is an excellent gift if one will accept it. You could even find it for yourself if you so desired.