Yes, I always carry in my truck.
It's no different- that's part of my point. If I am underway and actually driving, I see no reason for me to draw while moving. I can hit my brakes and stop and then deal with the issue, or try to get away without stopping.
If I'm riding- there is no way I can conceive of even trying to draw. You cannot fully control your bike if you have something in your hand. You really think you would have been able to pull a gun with a maniac in a car behind you?
The bottom line is- draw while moving? Just about never.