Spoilerish. Two astronauts tied together falling past a structure, once one of them grabs on and withstands the shock of the other astronaut snapping the tether taut, he should rebound back towards the secured astronaut, not dangle as if still being pulled by gravity. This would not be the case if, say, they were on a rotating structure or on a rocket making a significant burn but neither is the case.
My impression of that scene was that the cords tangling Bullocks' character were barely taught enough to stop her momentum and rebound, and if Clooney did not let go the cords would have broken at the other end leaving them both floating away. Like two people bungee jumping, while decelerating under tension, they notice the cord start to break due to excessive weight, so one guy detaches himself and falls to his death while the remaining elasticity of the cord is enough to save the other.