He's probably referring to the line of thought that most of a player's signature tone comes from the player, not the guitar. Certainly the guitar has an impact, but it's only a small part of the equation.

David Gilmour could hand me his black strat connect to his rig and I would NOT have his tone...I'd have some of it, but I wouldn't sound like David Gilmour (as much as I'd love to!!). I could hand him my Les Paul (or PRS for that matter), connect it to his rig and his tone would be there. Not identical, but it would be there. You would know it was him playing.