The right hand grip shifts on our other bikes work the same way as the Rohloff, so I'd say your SRAM Spectro is 'the wrong way round'.
Of course, the left hand shifters are the other way round, as are MTB rapidfire levers. I frequently find myself changing from middle chainring to inner on my work bike, when I really wanted the outer one. Irritating when you've been accelerating hard and the pedal suddenly drops away from you. Another good reason for having a Rohloff.
I take the point about a throttle on a motorbike working the other way round- sort of. Trouble is you're trying to compare a gear shift with power output, and they're not the same thing.
Perhaps if you imagine the movement of your knuckles as a metaphor for the speed you want to go, then forward is a higher gear (faster?), and backward is a lower one.
I don't suppose it will be a hardship for you to stop riding the city bike and just use the Thorn for everything instead, that way you'll get used to the gearshift.