Technically the answer to your question is no, since I don't think it ever was a core claim. But the subject of Saudi support for the hijackers, including financial support, has been an area of truther attention from quite early on. For instance, David Ray Griffin devotes 6 pages to the subject of Saudi financial support in his 2004 book on the 9/11-commission. More generally, my impression is that the question of who financed the hijackers has been a core concern for various parts of the 911-truth movement right from the beginning. ETA: It should be noted that the 9/11-commission in comparison only devoted less than 4 pages to the subject of financing, including the following to sentences, which aptly sums up the gist of the four pages: Especially the last sentence is often cited by truthers as a major point of disagreement.