The guy who built it is an artist. Not, I don't think, a biker, but someone who makes highly-unusual things and is able to sell them for $$$$$. Like banksy the graffiti artist who goes around making pictures which become 'works of ($$$$) art.'
So this guy made this, not to appeal to bikers, but to be an 'anti-biker' piece, using a really iconic item from the biker world, a H-D Knucklehead. Not 'anti-biker' as in, 'all bikers should be arrested,' but as-in 'what can I make that will use something really-important to bikers, but will be as-far as-possible from the 'biker lifestyle?'' A tongue-in-cheek poke at the rough, tough bikers. I'd say this piece (the motorcycle) accomplishes that.