I think the argument is that we have derived massive benefits from farming as a species that outweigh the amount of suffering we’ve caused in the process. I’m not sure I agree, but then I do eat meat.
Well, their argument is surely either "we benefited from X then, thus we should continue doing X now despite having other options" or it's "animals already do bad things in nature, so why care when we do it despite having other options?"
Neither of which is a very compelling position.