Yes, that's obviously taking the lifetime K2 deaths and dividing by the summit attempts - though actually I get 19% in that situation. However we really dont have enough data to form a good confidence interval there - it's possible we've had a lucky few years or maybe we've got better at deciding when to make the summit attempts.
But it doesn't really change my point. There's some threshold where it seems fundamentally immoral to hire someone for a job that has a good chance of killing them. Mountain porter on k2 or everest is a higher risk job than "astronaut" without the same glory that comes with the space faring job title. Even if the chance of death is 1 in 200, I still think its immoral to take advantage of someone who's so desperate for work that they'll overlook it.