In further support of your position, I believe Sasuke went blind abusing his susano'o. That and it is arguably the most powerful 'gift' their eyes have to offer so it seems strange that a person could use it after going blind or even without eyes whatsoever.
They have even mentioned at one point that you don't just go blind, but the blindness is a result of the power sealing itself away.
Almighty push was instant, wasn't it? I mean the physicist in me says 'well, it propagates at the speed of light'. But that would be near instant at these distances, and besides (come to think of it), I've never seen a retarded formulation of gravity. I believe it is always assumed to be instant.
Meh. Still find it offensive. I would have loved to see an actual almighty push used to clear the battlefield and push back the beasts, creating a crater like Paine did. I guess we should assume that Paine's powers were a poor approximation of Madara's (in reference to the rinnegan).