Show me the regulation prohibiting shooting a gun from a boat with the motor running. There isn't one unless you are pursuing specific game or waterfowl, and then it must be off and the vessel at a complete stop before you shoot. That's been in effect for waterfowling for years.

Wrong. Notice the "kill any bird or animal part".

220-2-.11 Prohibited Methods and Devices for Hunting
It shall be unlawful to concentrate, drive, rally, molest or to hunt, take,
capture or kill or attempt to hunt, take, capture or kill any bird or animal
from or by the aid of:
(1) Any automobile, motorcar, airplane, train, motorboat, sailboat or any
type mechanically propelled device, or any other device being operated
in conjunction with any of the above mentioned devices of
transportation. Provided, however, that nothing in this regulation shall
prevent hunting from a floating craft (except a sinkbox), including those
propelled by motor, sail and wind, or both, when the motor of such craft
has been completely shut off and/or the sails furled, as the case may be,
its progress therefrom has ceased, and it is drifting, beached, moored,
resting at anchor, or it is being propelled by paddle, oars or pole, and
provided further that nothing in this regulation shall prevent the taking
of game birds and game animals from any stationary motor vehicle or
stationary motor driven land conveyance provided any forward motion
is ceased and engine is shut off. Nothing in this regulation allows the
hunting, taking or killing or
attempting to hunt, take or kill any bird or animal from any vehicle on a
public road.