1. The black holes in the center of galaxies are indeed massive, but their
mass is much smaller than that of the galaxy (it is only about 0.1%), so
certainly it is impossible for it to supply the mass of the whole galaxy.
2. The angular momentum of matter circling the galaxy is many orders
of magnitude larger than what it could possibly have if it left the small
radius of the black hole, even if it moved there near the speed of light.
3. Most of the galaxies in which central black holes where found are not
disc galaxies at all. They are spherical or elliptical galaxies, which
do not rotate. So this picture would not fit them anyway.

Thanks for the clarifications Hezi, As I said earlier, I don't wish to
start a discussion on the subject. I hope you understand.
All the best and good luck with the theory.
Moti Milgrom