Rewatched the scene a few times and talked to some people on Discord, and this is the best interpretation I can come up with regarding the gravitational inversion. We're delving into the realm of pseudoscience so it's not really easy to quantify but this is the best way to view it in my opinion
So watching the scene, this is what I think the movie is trying to say. Keep in mind this obviously violates multiple physics principles
-They enter from the entrance, Kong swings for a bit before free falling towards the centre of the Earth due to gravity
-They pass through the Hollow Earth's boundary, and suddenly gravity "inverts" to being outwards (towards the surface of the Hollow Earth) instead of inwards
-However since they were originally free falling, they have a velocity in the direction against the surface of the Hollow Earth
-Hence, they decelerate at a high magnitude, hence the "1000 miles in 2 seconds"
-After they were thrown 1000 miles we see that the ship stops and Kong and the ship suddenly starts falling in the other direction, which is the gravitational inversion
So it isn't really the ship being crushed by the weight of a planet (that's not how gravity works lol), but it was subject to a force of 1.61 billion Newtons (assuming it weighs 2 tonnes, about a heavy car).
A nice lifting strength feat for Kong crushing it, but worth nothing regarding AP.