-
I was just curious to see whether there's a big argument for or against
The argument for having spokes swept that way when driving forward is that the displacement tends to expand the rim, so it tends to stay flat rather than collapsing into a series of axially displaced waves. Look at brake discs and you'll see that any competently designed one is made this way. On a wheel which is going to be driven both ways from the hub (acceleration and braking), having the spokes swept only one way is going to be wrong for one of the directions of torque input. In the case in point, both wheels will tend to collapse under braking loads, a problem which can only be mitigated by making the rims very stiff. Since deep crabon rims tend to be very stiff anyway, it's not likely that the wrong spoke orientation will cause a problem other than making it obvious that the person who came up with concept is pretty clueless, and there's more than enough evidence of that even if you hide the wheels.
There's your answer; it's a concept bike, so it doesn't have to make sense