It wasn’t Vettel’s fault for sure. Vettel did what any pole sitter would do, protect his position going into turn 1. His nose was way ahead of Max’s and therefore he had the right of way. If you watch the replay in slow motion, you will find that just before the contact between Kimi and Max, it’s Max who veers to his left ever so slightly, in response to Vettel pushing him wide and then doesn’t correct himself. So he keeps drifting to his left, and into Kimi.
But I can see why the stewards decided it was just a racing incident. It all happens so fast. Max gets overtaken by Kimi on the left, just as Seb is pushing him wide, and Max’s small steering input to the left is enough to cause the contact. He had very little time to react and his instinctive reaction was to avoid the car he could see, not the car that was creeping up on him from the left, at that exact time.