Hey pals. You're probably aware of those products that let you use mouse and keyboard on a console. Apparently it can't be detected and you're totally safe.
What if the game simply checked for foward/back or left/right inputs being hit at the same time? That would be a dead giveaway. So would instant 100% movement instead of gradual movement to 100%. Even an instant flick would have acceleration on a stick.
I think they probably can detect it and just don't care.