If models become very capable and resist having their objectives changed, the speaker believes there may be only one good opportunity to set their objectives beforehand, since changing them later will become difficult.

“But if we get to a point where the models are very clever and they don't want to have their objectives changed,”

“it kind of means we only have one really good shot to set their objectives ahead of time because otherwise it's going to become quite hard to do it down the road.”