Yeah, that's what I mean. There's no particular reason Will should be considered the original except from the perspective of his peers. If there were still people on the ground when Tom rematerialized there, he'd have witnesses and people ready to argue that he was the original.
And after all, what if the entire beam was reflected and just one Riker materialized on the ground? If getting through to the ship is what defines the original, does that mean he's not? I doubt he would be considered a copy merely because he didn't make it to the ship. (That is: any more than anyone else is considered a copy by screwy transporter logic.)