You can safely ignore this side-quest when it pops into your game temporarily.
We do not know exactly how this happened but this appeared briefly in the list in the game and then it went away - shortly after the second of the Outpost quests was completed. So the assumption is that it is a programming error - the important thing is that it is not a legitimate quest and therefore does not count for the total for the Achievement.
We successfully unlocked the Achievement for doing all of the side-quests after this one disappeared from the list and you should too....