We don't need the parachutes to make sure that the asteroids are flailiny through the air and touch down gently on the surface. We're just using them to shave off the speed of asteroids by a couple of orders of magnitudes.
Also, I don't understand the need for shielding a literal mountain. We could simply write off a couple of feet of exposed, ablated material and extract the stuff inside.
At present, there is no (actual) commercial technology for doing deep sea mining
Sorta like how at present there is no commercial technology to grab and divert huge asteroids. Even if we assume that such a technology would never develop/ be viable, couldn't we just aim it at the vast deserts with soft sand to absorb the impact?