Blocking a robot driving clock-wise

[hipsterjr]

If you are talking about post hurdle and before they retract their arm. And by being behind them, you want keep them from being able to retract their arm.

I would say yes, this is legal (to a point) because they are no longer protected by the hurdling rule. But I would use caution in this strategy because of the excessive contact and possible severe damage to the hurdler may incur penalties for you. If do, please be gracious about it.