A "Conspiracy Theory" and a "Theory of a Conspiracy" are different.

The phrase "Conspiracy Theory" entered the language after the Kennedy Assassination as a shorthand way of dismissing any theory of wrongdoing that would require so many conspirators that credulity is stretched.

A "Theory of a Conspiracy" is any theory of wrongdoing that requires more than one actor.

Calling something a Conspiracy Theory and then retreating, when pressed, to "it's a theory that requires more than one actor" is, IMHO, sophistry.

BTW: My answer to "Conspiracy Theory" in the Kennedy case is that the high level government cooperation in promoting the Lone Assassin fairy tale was based on a "secret theory" being proffered inside government: Kennedy was killed by Castro & the USSR in retaliation for Kennedy's attempts to off Castro. Since he "had it coming", there was no sense in starting WWIII over it, so they fed the public a line for the good of world peace.