On the Fatima Center website, Mr. Ferrara attacked the sedevacantists for what he calls self-contradiction, a “fatal flaw” in their thinking. He first accurately sums up the sedevacantist position:

So, according to sedevacantist thinking, one cannot legitimately recognize yet resist a true Pope because while not every papal magisterial act is infallible, every papal magisterial act is (1) authoritative, (2) binding on consciences, (3) safe to follow, and (4) free from pernicious error. [emphasis added]

He then proceeds to attack this position as containing a contradiction.

What the sedevacantists are really saying, then, is that a Pope who errs in his teaching on a matter of faith and morals, even once, ceases to be Pope (or never was Pope) because every exercise of the papal magisterium must be free from error.

Notice that the word pernicious has disappeared. In leaving this word out, Mr. Ferrara has manifested that he does not understand the whole point of the sedevacantist argument.