He plays it like a baritone guitar - more Tony than Geezer - which I guess you should. It's not that the E, A, D & G strings (if you use bass and not baritone tuning) can't provide a bass sound on it (though nothing even close to the might of a mudbucker), but the narrow spacing makes it feel entirely guitarish and the C and F strings (or B and E if you use guitar interval tuning, I can never make up my mind whaat makes more sense on these) do sound quite differently and very un-bass'ish. It really is an instrument for which you have to rethink your style and approach.
Bruce Springsteen started out with one of those and not realizing that it was a bass tuned it EADGBE
at the guitar octave (not the bass octave!). He forever wondered why he had such a hard time pulling strings and could only chord with a lot of strength on his 30" scale 'guitar'. Until one day someone told him!
(Perhaps the bass tuners should have made him think.) I would wager the guess that playing that thing like a guitar did influence his forceful rhythm guitar approach.