It's not so much vetting their thoughts, as dealing with my own inner voice ranting at the beliefs I see in their writing.

There's a few other books that I've been unable to finish purely because I disagree with the author so much that I just can't read their work. I end up shouting at them (sometimes actually shouting at the book) so much that that forms my engagement with the text and it becomes pointless trying to read any more. At least I managed to finish Terra Ignota.