For decades, all sorts of devices with very simple processors have been able to detect when the force against an actuator exceeds a certain amount and reverses or disengages it.
Yes, but how do you infer intent from the force put against the actuator? There is no point in using this robot if it doesn't work if people are heavier than some arbitrary value, or if they get released because they bumped against something while being towed...
Also, if it can spot an incapacitated person amongst all the other swimmers, then it must be able to recognise when people are not incapacitated, otherwise it would just be going around randomly grabbing swimmers.