The only evidence I have seen, is that put forward by Laurie Daly last night when he claimed the Grapple first appeared in 2003 by the Storm in a match against Canberra. He showed images of the tackles.
So if I dug up images of similar tackles before the Storm even existed would that refute the argument?
This whole grapple tackle issue is a self-fulfilling prophecy. A lot of people want it to be true to make themselves feel better about their own lack of success. To do this, they jump on anything that helps prove their argument to the exclusion of anything else.