There's a bit more to it than just doing the numbers. Checking to see if the passengers can wear a life jacket and can fit in the seat belt are done after the numbers. I would check and brief my CP to check and make sure that the portly passenger would not just pull up his belly, lay the seatbelt in his lap and let his belly cover up the buckle.
It's good to see drilling companies begin to take the matter seriously. It will be interesting to see if they apply the same policy to the service companies, because that's where the bulk of the problem lies.