...why is the front brake caliber on backways on the raven
...And my Nomad!
I can't speak for Andy Blance, jags, but it likely allows the fork blades to serve as an integral brake booster. With canti-/v-brake posts on the front of the fork, braking forces (pads grabbing the rim) tend to bow the posts outward, causing squeal and judder. Putting them on the rear of the fork means braking forces tend to draw the posts inward...a bit like on rear brakes.
It seems to work for me, as my front brake is quiet as can be and braking is as smooth and powerful as anyone could ask for (I'm running plain Deore v-brakes with Kool-Stop Salmon pad-inserts and Tektro RL520 levers on drop handlebars. Two-finger braking from atop the brake hoods will result in "stoppies" on the unladen bike).
It also has the happy result of placing both adjusters on the same side of the bike (convenient) and give the front of the fork a nice, clean appearance (bonus points for aesthetics).
Best,
Dan.