I would consider cutting off 3" inches or so to make it easier to get out. Cutting that off will drop the stair depth down to typical height. But I will say that making 2 straight and even cuts on the stainless pipe will be easier said than done.
Now that I look at your pictures a bit more closely, it looks like the left leg (as seen from sitting in the water) is not on the flat wall of the pool, rather it sits on the start of the curve? Is that true? If so, I expect that this might be a huge part of your problem.
Is this is not true, with regards to the bending of the tubing, I will try to explain. The dimension that matters is from the parts that goes down into the mount of the deck, to the vinyl liner wall. I am going to make that number up for right now for the purpose of this discussion, so don't quote me on this next number. But lets assume that dimension should be 12". If you made the dimension 11.9 inches, that means the bumpers wont naturally rest against the wall, rather float about 0.1 inches off of the wall. Once under force when you use the ladder, your body weight will force the bumper onto the wall, thus your seeing movement and rubbing. However, if you would have installed the stairs 12.1 inches away from the wall, then you would have had to stretched the stairs to maek them fit. This slight stretching would cause constant force to be applied to the wall, and this woudl mean that when your body weight got on the stairs, they would not rub. So the idea is if you bend the stairs slightly, you make the gap smaller, adn therefore put the stairs into a constant state of force.
Now with all of this said, side to side movement will happen no matter what. And as I started, I think that your issue might be that the stairs are not on teh true flat wall.
