In my defense, Sitar wouldn't know that the bikes can keep going on autopilot. And fortunately I was also vague enough with my wording that I didn't specifically say the bikes stopped. My wording was that without the riders the bikes should stop, but again, Sitar obviously doesn't know about their autopilot feature yet.
It makes sense he shouldn't know that, absolutely. But the thing is the bikes shouldn't have drivers in the first place if they're the ones retreating with the slaves as they're already auto-piloting back while their drivers stay behind to capture more slaves.