First of all the quote used does not give a definition of "government", it only uses the word. To answer your question "what if that external control is voluntary?", if you voluntarily agree to something then it is consensual, if your are being "controlled" then it is not. Every individual has contol over himself so if he CHOOSES to to follow external command then it is ultimately his choice thus making it consensual. There is no option to opt out of "government". Do you think freedom is trivial? Also can you delegate a right that you do not have?