There likely is a lot going on there. I assume you guys are all using
wave boards, or something that isn't going to pearl on every drop in.
Lots of rocker and pretty soft rails. Wave sails or wave-like RAFs.
If that's the case, what he's doing is allowing the board to ride a
bit more free of the chop and at a higher top speed. If his sail is
that high, so are his booms -if even an inch or two. I would bet his
mast foot is also forward a bit. Wide lines are long lines, and the
roller bar allows him to reduce the amount of sheeting power without
reducing sheeting angle -just a bit more than a std. bar.
He rigs like Robby Naish used to do. Huge triangle for control and
speed. It keeps the nose high and even, and makes for a very
comfortable ride. Confort means confidence, and we need confidence in
our fin grip to go faster, and speed is the only way to get the fin
really firing. I bet your friend is getting close to actually riding
the fin at times.
I suspect this may be what's happening.