I see where you are coming from though, and it is an intriguing POV.
I don't know if you are into the EU or not but Mace Windu is supposedly the master of a lightsaber form that he created called Vapaad. It is named after a many-tentacled and very dangerous creature, probably because of not only its lethalness but how close one must come to the dark side by using this form.
Maybe since he comes so close to the dark side, Mace uses a saber color that mixes both traditional Jedi colors and the colors of a Sith.
Crackpot theory and worthy of TF.net if I do say so myself.