Cargo shifting is a big deal. The yearly casualty rate for Bering Sea crab fishing used to be over 1% per year, because the shifting weight of crab pots on overloaded vessels in heavy seas. I saw a training film when I was aboard a tender boat in Alaska. Those boats could look fine one minute then capsize and be as good as sunk in the next 2. Shifting weight on vessels has and does cause rapid capsizing and deaths at sea.
This is pretty light cargo relative to the weight of the ship. It's a few tons of rocket and thousands of tons of ship. I don't think it's going to matter to the ship if it shifts, the only risk is losing the rocket over the side.
What you say is True. My comment explains why the shipping industry and regulatory bodies seem paranoid about shifting weights at sea. There are good reasons to be conservative about certain things and brook no exceptions.
