A conspiracy theory is about two or more people having been manipulating things in an illegal way. If Zagami has been lying and only him, then it's not a conspiracy. However, also Basco must have been lying since in the lawsuit it says on page 41:
"During the course of those discussions, DAL BOSCO represented to KEENAN not only that he was the financial advisor to Zagami, but also to the Vatican, Vatican City, Rome as well as the Treasurer of the P2 Masonic P2 Lodge in Rome and Monte Carlo working directly with Zagami."
This means that for my initial statement to be wrong at least two persons must have been lying, which is a conspiracy theory.
The only exception as I can see is if the persons in the lawsuit don't exist at all and have been made up by only one author, in which case it's fraud but not a conspiracy (since only one person would then be involved).