We could argue that its "unproven". As in, the absence of positive or negative proof. And I would also add that that statement isn't actually proof for or against the greater claims Q makes.

But disproven would mean negative proof; a level of investigation that renders the position taken logically impossible to occur.

Proven would mean conclusive positive proof.

Neither exist, because one would require the literally every investigator in the nation to dedicate the next year solely to checking out all the closets of everyone of note in the nation, and the other requires a healthy amount of elites hanging from the rafters.