So you think that in 1958 Cardinal Siri was elected Pope, but then the Cardinals forced him to abdicate when the Soviet Union phoned in a threat to nuke the Vatican? And that Siri was elected Pope again in 1963, and twice in 1978, before being forced to abdicate again in each of those conclaves, so that therefore, neither John XXIII, nor Paul VI nor John Paul I nor John Paul II nor Benedict XVI are legitimate Popes, because the real Pope (the Pope in exile) was Cardinal Siri aka Pope Gregory XVII, who was Pope from 1958 to 1989, and that since Siri's death in 1989 the Church has been without a Pope?
Because that is what Malachi Martin believed, and it is, by comparison, one of his more sane and rational opinions.
The sedavacanists have their "theory". If Fr. Martin said this, I certainly disagree and this is a dangerous position. However, this theory in itself does not negate the truth of things that he has personally witnessed and writes about. We can't say he is a liar since he (perhaps) holds to a particular theory that is theologically unsound. Writing about things he has personally seen and heard is one thing; writing about personal theological opinions-even perhaps based on hear-say is another.
I suppose that if what you wrote is true, I would not suggest to anyone picking up his book incase they can't make such distinctions as they read.