That is written weirdly and hard to know what really happened. Two people stuck on a pinned raft in the Grand is hardly a reason to call in NPS. They said they had experience so hopefully they tried to self rescue. If they honestly tried every scenario and then a few jerry rigged ones then maybe. I also wonder about trip participants that cause worry if they hit the water. Granted Hance would not be a pleasant swim, but it is still pool drop. Just seems like an overreaction to the situation I read.
If you can't reach the boat with one rope, use two.
Ferry a boat out off shore to get a rope to them, or derig to a paddle raft and paddle out to them.
Use a strong swimmer rescue to get people off the raft and not swim the entirety of the rapid.
So many options and plenty of time to try things with the scenario they described.
Take along a kayaker who can get to a raft pinned in the middle of a river and offer options