Not sure if this will add any value to the discussion or not.
To my mind, this is a good comparison to make. Grosjean squeezed Hamilton out from a position where he most definitely should have been aware of Hamilton's car. He also made the move with a clearly evident car overlap, while he was drawing away from Hamilton.
Rosberg closed the door with less evidence of car overlap. At the time he committed to his movement, no overlap existed, but Hamilton was moving extremely rapidly into a decreasing space, having also committed really early to his attack. Note, there is even less space for Hamilton to move across in this case than in Belgium.
With nowhere to go, Lewis did make an attempt to back out, but it was too late.
All in all, extremely unforgiving driving from the pair of them, and just goes to show the dangers of making an assumption with no margin for error. Rosberg assumed his closing of the door would be enough to ward off the move, and Hamilton assumed Rosberg would be less aggressive in his defence.