2G4 itself has very high immunity to conventional RF interference, so the radio part deosn't benefit from suppression.
However, the rest of the wiring makes a very good set of aerials for picking up electronic noise generated by an unsupressed motor, and can give many hours of head scratching wondering why intermittent random happenings are happenning, not least because it never happens on the bench, only out on the water.
If you do have an unsupressed motor, any friends using the old frequencies might not appreciate your offering a travelling source of interference.
I have never been a fan of soldering capacitors to motor casings, having the belief that more components is more fault liabilities, and personal experience says that with modern permanent magnet motors, just one capacitor across the motor terminals does the job. A very few pennies and minutes early on saves a lot of potential problems later on.