Throughout lecture and with our own personal analyses of The Lives of Animals, we have spent a large amount of time trying to figure out what Coetzee's perspective is on animal rights. Does he agree with Elizabeth Costello? Or the daughter-in-law? Or maybe some other character completely? But I think we're focusing on the wrong issue.
The series of lectures, and even the responses that come after it, is showing us that there are many perspectives that people can have on this idea of animal rights (as with any issue!). There is never a whole consensus, someone is always there to make a counter argument, and the debate can last endlessly if so desired.
Coetzee, I believe, is trying to discuss that idea more than necessarily actual animal rights. I think he's trying to show that there will be never be a view that everyone can jump on board with for this issue and others like it. He's, instead, trying to have the reader understand the importance of thinking about your viewpoints and assessing them critically. I believe he's also trying to illustrate the importance of when you find a viewpoint that you can agree with to not be easily pushed and persuaded by the counterpoints of other perspectives (again referring to the idea of thinking CRITICALLY). Costello, the other members at the dinner, and even the daughter-in-law all have perspectives that they stick to despite other ideas being thrown at them.
I think Coetzee could also be critiquing the way other people look down upon other people's ideas. The daughter-in-law is portrayed as being rude and disrespectful towards Costello throughout the story in a way that made me dislike her (which I think was the point). By making her seem this way, Coetzee could be trying to point out the difference between standing behind your viewpoint and being disrespectful to people. People should, once again, think critically about what the other is saying because it could be reasonable enough to morph your ideas. After deciding how to view the new knowledge received, they should then acknowledge the importance of it, whether they decide to agree with them or not.