I never understood that quote.
The Sith are far more whimsical than Jedi, and thereby not really absolute at all. Anakin, for example, has a secret love affair; so love is something that Sith are allowed to explore. Love in its very nature is a non-absolute because it's based on emotions. Further, the Sith are far more emotional than Jedi, and therefore far more unpredictable, making them less absolute.
It was one of Lucas' dumbest lines when one gets past the fact that the statement itself is an absolute statement.