Well, the way I understand it, the spheres were connected to each other by an attraction force. We see Hulk punch one of them away while still holding on to the other. If the second, still stationary, sphere had instantly started to move at escape velocity, the Hulk would not have had the chance to react, he would simply have been instantly swept away along with it the moment of his punch.
However, this is an old Chris Claremont story, and that writer has never let such a thing as consistency or accuracy get in the way of a plot.
So instead we see Spider-Man, who has never been demonstrated as thinking at vastly superhuman speeds until then, managing to form several coherent sentences, move the Hulk (If he had hit with escape velocity speed and force, and this story followed the laws of physics as closely as you think, the Hulk would have been launched away from the planet anyway. He only weighs a bit over 1000 pounds), and point at the spheres going away into the sky.
All in all, this seems very unreliable to me.