Stirring the Pot of Machloikes: Righteous Act or Sin?

Source Sheet Yalkut Shimoni brings some of Korach's clever arguments. Rameh M'panu says that husband and wife in story of Bava ben Buta and R' Meir were gilgulim of Korach and his wife. Rav says in Sanhedrin that one who is involved in Machlokes transgresses a Lav. Do you violate a Lav for being involved in a Machlokes? If yes is it De'oraysa or Derabanan? If yes, which Lav? Rambam vs Ramban Is it a Lav to challenge the Kehunah?Parshas Korach