How could it be anything other than that.
Lewis ran off onto the grass to avoid the car in front of him.
Completely lost control.
Went side wards and hit the car in front of him, taking them both out in the process.
It wasn't as if Nico gained from being trashed.
Number of moves made, in relation to the racing line, and motive will be the big questions.
I personally believe Rosberg got caught out and made a split-second decision that turned out to be the wrong one. I don't think he should be penalized for it.