I think the violet-tinged lightsaber is quite in keeping with the concept of a grayer non-Sith Dooku, so I’m not keen on the decision to switch over to a standard blue. You must do what you feel is right, of course.
I did this because although he is morally grey, his motivation in my edit is selfless. Similar to how the Jedi Order’s inaction towards the injustice within in the Republic was morally grey, but they remained to the Jedi Code, not acting out of hate, etc.
Remember that in The Republic, The Trade Federation is legally allowed to starve a planet even before they became associated with The Separatists. Dooku believes that the selfless path is to save the galaxy from the course it has been on for a while now, towards fascism and the dark side. Dooku wants to prevent this before it comes to pass. When said like that, it doesn’t sound very “sith” he is still a villain because of the methods he uses, but ultimately acts selflessly.