[EricH]

With respect to the strategy, you should be fine. Just don't go chasing after anybody within range of the Alley; that could be seen as a violation of [G45].

With respect to the spinning arm, that's something that depends on implementation. I wouldn't call it unsafe just based on the short description you gave, but the inspectors who see it will have a better chance to tell you whether it's OK or not OK. Because it's always within the Frame Perimeter, you have a higher chance of not being found in violation of any safety rules, but I would suggest adding whatever shielding/lockouts/pins/brakes you can to make it safer.