Apparently in 1.6 he removed HIM, then
in 1.7 the update notes had "- Removed Herobrine"
Negative of a Negative is still negative, 1.8 contained "(*)Removed Herobrine", Multiplying a negative gives you a positive (MATH).
In 1.0 i dunno what it said before "Removed Herobrine"
But in 1.1 Herobrine wasnt Removed, let's say he's in game, then 1.2 came out as a negative, Positive "MINUS" (because 1.8 was times.)
So Herobrine was neither added or removed.
(I HAVE ALMOST NO CLUE ABOUT NEGATIVE/POSITIVE RULES)