Scrivs has long been the face of the Legends, even before the Legends were formally established, but I don't think it necessarily follows that he is a key player in this bid, especially if as you say, he is unwell. The wider Wasps Legends group (beyond the ex players that we are familiar with) includes donors to the charitable foundation, and any number of those may have significant wealth in their own right, so may well be person(s) less well known stumping up the cash, with a smattering of more familiar names from the ex-players' side to be the face of the bid and make it more appealing to fans and media.
I'd be very surprised if Rigby isn't in there somewhere. Ex-owners were mentioned when this story first broke. Didn't the club briefly pass through Riggers' ownership in between Hayes and Richardson? Otherwise, the only ex-owner I can think of as being remotely likely to be in there is Wright.