There was a chapter in his book “Starry Messenger” dedicated to this subject. I unfortunately cannot reproduce the entire chapter here. However, here is a video essay on it that you can watch if you’re interested. https://www.youtube.com/watch?v=wbXw13Npvlg (25min)

One of his dumbest argument imho was trying to claim that vegans were specist towards plants, even though no scientific existence of sentience in plants exist which is the moral criteria used in most anti-specist philosophy. I will add that even if plants were all found to be sentient, we’d still kill less sentient beings by eating them directly rather than feeding them to non-human animals and then killing them.

Here is another video of him talking about this very chapter for example: https://www.youtube.com/watch?v=z9HrMdNEKPA (6min). I think this shows a complete misunderstanding of what veganism and anti-specism is about. To me it seems like he does not even consider the sentience of the animals and considers them as machines. He also seems to straw man the position to “vegans want to protect life”.