He is hated by all Russians and if he somehow miraculously becomes president, then mass rallies and protests will begin. It will be even worse than in Ukraine. Kadyrov has no chance to become president until Russians recognize Islam 
You are wrong about that. Kadyrov's net approval rating is in the positive. A lot of ethnic Russians and other white minorities such as the Germans and the Chuvash admire him. And although he is a religious Muslim, he is extremely tolerant about the other faiths.