You’re getting pushback because it sounds like you’re not aware of the circumstances. The movie takes pains to make sure viewers understand the stakes by showing what happens when someone panics during an underwater rescue.
I’ve actually seen this firsthand and it puts everyone in danger. When it happened to me, we were only in about thirty feet of water. I was able to get the woman to the surface only by seizing her buoyancy vest with both hands, pulling our masks very close to each other so she could only see me instead of the open ocean, and trying to reassure her with however much of my face she could see. And she even had some training! It was her checkout dive after several classes in a swimming pool, so she knew how the equipment worked and she had of course been taught about the dangers of rapid ascent. But she wanted nothing more than to get back to the surface as fast as she could and I had to hold her tight the whole time as we slowly ascended. It was almost like riding a tiger. I could feel her body struggling to just go up, up, up, which could have seriously injured her. But she was panicked, and her body had taken over.
Now imagine this in a completely dark, tightly confined, and jagged underwater space, with a child who has no concept of how scuba gear works. It would have been madness to take those children through while they were conscious, and given the circumstances, it was incredibly risky dragging them underwater for upwards of seven hours and having to regularly re-administer the anesthetic as they went, regardless of whether it was ketamine or anything else. The actual medication was hardly the issue!
So suffice it to say the situation with the Thai rescue was well within the boundaries of no anesthetic being completely safe. And I didn’t even need to use quote marks! :)