I believe you are interpreting this statement incorrectly. Once Madara left the village and began to attack it and try to destroy it he lost his right to be considered part of the village any more. Hashirama was not talking about the founding of the village he was saying Madara was no longer a part of it any more.
I disagree with your statement about Senju being tyrants. Not even Tobirama and his prejudices rise to that level. The only tyrants I see are the ones who think they can put the whole world under a genjutsu to create a world that suits their desires and enslaves all the people living in it. The only tyrants I see are Madara and Obito.
Dude, THANK YOU!!! Exactly what I was thinking