Not quite. Cardinal Siri actually did recieve the required number of ballots to become Pope in both 1958, and 1963. But in both cases he refused the pontificate, citing danger to his family, friends or even to himself.
That much is recorded fact. The not too subtle rumor is that the secrecy of the Conclave may have been violated, and a message passed to Siri from the outside world, indictative of such a literal threat.
Perhaps you would like to post a citation, from a non-conspiratorial source.
Is this another of your goofball Masonic fictions?