It's well-documented that Hatsumi learned Togakure Ryu and the other arts which go into the Bujinkan from Toshitsugu Takamatsu, so if the scare quotes around "discovered" are meant to indicate that he actually secretly fabricated the art, then that accusation should be aimed at Takamatsu.Considering Hatsumi's Judo background before he "discovered" Ninjutsu, that doesn't surprise me.
I considered that there might be some judo influence in the technique, but I've never seen that particular sequence (jump guard to double ankle grab sweep to kick) in any judo reference. Elder could probably tell us if there's some obscure judo source for the kata.