From all of the above postings it seems that "live unknown" can relate to the following list of ideas:
--Don't try to make a name for yourself
--Don't do things that put you in the spotlight such as becoming a politician
--Don't teach Epicurean philosophy publically
--Don't get involved in politics (political activites or political debates)
--Don't be concerned with being known after you die
--Don't take on (espouse) the groundless ideas of the crowd
And there are reasons for "why" for all of the above are important to consider, although it should be understood that there isn't some kind of absolute rule against these. If your life is beginning to move into a "hellish" direction, you may choose to do something to prevent it from getting worse.
If your life is going well and there isn't any extremely pressing reason to publically engage in politics, then take heed, because you are highly likely to end up creating a "hellish" life for yourself, and you will have ruined your chances for enjoying this one life. (Perhaps in modern times we have more room for consequence-free expression of opinions because of the internet).
In addition to the above, I see "live unknown" as the start of the consideration of whether or not we "owe" time and energy to upholding the well-being of the city-state/nation/commons. If that kind of action gives you pleasure, then go ahead (but you will likely encounter difficulties). If it isn't something that comes naturally, then don't feel that you are doing something wrong by not getting involved. If things around you are going downhill and you need to protect your life necessities, then of course take action. And since everything is politically polarized, don't be surprise of bad consequences that you encounter when you do take action.