Treason is a crime. If it can be proven that the Russian government interfered in the presidential election, giving aid to a foreign adversary is treason. I'm not sure it matters whether he knew, especially if it can be proven that members of his campaign participated.
that said, we only have the word of the intelligence community as "evidence." that's not good enough for me. it's funny how everyone thinks they know the result of the probe before it is over. I feel like The Atlantic might know more than Mueller at this point.