As far as I know, everything, once it crosses the event horizon, is causally disconnected from the exterior. (I. E. There is nothing you can do from the outside, that will affect the inside)

I don't think any special physics are required to explain this other than general relativity. Any changes you make to a black hole cannot fully manifest until the end of the universe. So I guess you COULD gravitationally distort an event horizon, but from the perspective of someone inside, the distortion happens at the same time as everything else (which is all happening at once) at the end of the universe.