Good point. I read the thread a while back where AGK recomended removing the govenor because at very high rpm that his motors make the plastic gear could grenade. He didn't mention about the arm causing probs. It would be logical to remove the arm if the motor is opened to remove the gear.
If one wants to leave the gear and not open the motor, I believe that they should leave all of the external govenor parts intact, except for the friction throttle and reversing the spring, to keep the arm from moving more than it's normal range.
The other more dangerous concern with his high revving motors was the chance of the stock flywheel exploding. Also, I've read someone here that had a problem with his plastic flywheel fan coming apart.
Surely the crank striking the arm can't be good. But it looks like the rotation direction of the crank would tend to knock the arm away instead of getting caugt up. Sorta like sticking something into the front of a spinning fanblade, it gets knocked away, not pulled in.
Maybe that's why this hasn't been an issue with those that removed the bellcrank.
I don't think that exploding parts is much of an issue with a stock motor. The valves float, limiting the rpm on mine to just a tad over 5000 rpm.