Maybe he desperately needs attention?
Fr. Altman goes down the sedevacantist path. He's responsible for his actions, of course, but I also blame his bishop for essentially kicking him to the curb for political reasons.
The modern understanding of Sedevacantism is that the Pope reigning from St. Peter's Chair is not the Pope. Now we may privately doubt this. But we cannot declare. Does Father James Altman have the authority to declare? No, he does not. Moreover, he is in danger of turning a private conclusion into a dogma = new religion.