I don't see how Siri could have had a chance of being pope, given that he did not accept being the Pope. One is not forced to be a pope if elected. If an elector refuses, as is his right, then he cannot be said to be pope.
According to the theory, though, he did accept. Paul Williams (the former FBI consultant) indicated that he accepted and took the name Gregory XVII in the 1958 conclave. Not only to you not take on a papal name, but also there's no white smoke send out unless and until the candidate has accepted. As soon as someone accepts, he becomes the Pope. Once he's the Pope, then, he cannot be forced to resign under duress (that would render the resignation invalid).
This is actually an act of diabolical genius. See, these Mason/Communist/Jew operatives knew that a legitimately-elected Pope (even if he were an occult heretic, even a malicious infiltrator) would continue to be prevented by the Holy Spirit from damaging the Church this way, even if it meant that God would strike him dead. That is precisely why they waited until Siri had been elected and accepted to come in with their threats. They could have done so anytime before the conclave, told Siri up front that if he gets elected, he should refuse the election or else [whatever threats they had in play]. But to pull this off, they needed Siri to get elected and accept, in order to render the subsequent election illegitimate, so that the candidate was not the Pope and therefore not guided by the Holy Spirit (or at least prevented from teaching grave error to the Church). It was a masterpiece of diabolical genius.
Masons actually thought they had their man on the See in Pope IX, but after Pius IX was elected, he had a conversion experience ... that came by way of an armed attack by the revolutionaries. In fact, he was so liberal that a Cardinal was on the way to veto his election, but he was elected before he could get there. From being a notorious liberal and welcome by all the same individuals who pulled off the Masonic revolutions in 1848, he turned into one of the most staunchly anti-"Modernist" (before St. Pius X had coined the term) Popes in history.
Sadly, these Illumaniti/Masons/Jews/Communists had more faith that the Holy Spirit would prevent a legitimate Pope from destroying the Church than R&R do.