The synopsis of that book reads like (yet another) sedevacantist hit piece. As if we were extremists to be completely avoided like the Westboro Baptist Church or the Branch Davidians, note the association made to the Palmarians and their "canonizations" of Hitler and Franco (Franco did very little wrong, but he wasn't a saint).
I'll admit the potential for doubt regarding the mental state of Archbishop Thuc if we can also admit doubt regarding the consecrations offered by Bishop Mendez, given he was within the Novus Ordo religion at that point. Neither of which I believe are doubtful, personally.