The theory behind spiral galaxies is that a black hole of considerable magnitude and time lies right in the center. Gravitational waves spirals out for millennia. They start moving towards the center but also move towards each other. Closest stars move towards the center and other stars begin following the close stars and so on. This should ordinarily end up like an octopus with multiple arms extending from the center outwards. But then the Universe must also be rotating like a disc. And so the galaxy spirals out with curved arms instead.

So, yes, we think there is a massive black hole at the center of all (or just spiral?) galaxies. And gravitational waves move at the speed of light, so if something changes the mass of the central black hole, and the galaxy has a radius of 25,000 light years, it will take 25,000 years for that wave to propagate out to the rim of the galaxy, rearranging things along the way. But:

1. The massive, central black hole did not come from a supernova. There are no stars anything like that big.

2. Even if there were a huge central mass and it collapsed, that doesn't actually change the mass distribution as far as the rest of the galaxy is concerned. There is very little change to propagate. The existence of the huge central mass would have already "arranged" the galaxy.

3. Galaxies spiral with curved arms due to their own rotation, not due to the universe's rotation. If the universe were rotating like a disk (and that was causing the spiral of galaxies), then you would expect the spin of galaxies to all be aligned. And they aren't; not at all.