What do the Sealanders think of wacknuck

This answer can be found at the very end of the story. David has been rescued by the Sealand woman, and the conversation that follows gives David and readers great insight into exactly how the Sealanders view the Waknuk people. As the Sealand woman explains that the plastic threads contract enough to kill anybody caught in them, Rosalind shivers at the thought. The woman's nonchalant attitude toward the deaths of all of those people surprises David.

We were puzzled, too, by the Sealand woman, for there was no callousness in her mind, nor any great concern either: just a slight distaste, as if for an unavoidable, but unexceptional, necessity.

The very next paragraph has the woman explaining her apparent callousness. She explains that death is necessary in order to put meat on the plate in order to eat. This comment doesn't mean she thinks the Waknuk people are a food source. Instead, it shows that her attitude is that the Waknuk people are equivalent to an animal of some sort. If readers question this concept, the Sealand woman makes it abundantly clear at the end of the paragraph that she consideres the Waknuk people a completely different species than her own.

"And just as we have to keep ourselves alive in these ways, so, too, we have to preserve our species against other species that wish to destroy it — or else fail in our trust."

The woman believes that Waknuk people are an inferior species that is now being naturally selected to eventually disappear from the planet.

"Your minds are confused by your ties and your upbringing: you are still half-thinking of them as the same kind as yourselves. That is why you are shocked. And that is why they have you at a disadvantage, for they are not confused. They are alert, corporately aware of danger to their species. They can see quite well that if it is to survive they have not only to preserve it from deterioration, but they must protect it from the even more serious threat of the superior variant.
For ours is a superior variant, and we are only just beginning."