I really don't think this is about causing injury or even an issue of dangerous play. His intent (if he has any) is to wind up an opponent. He has various techniques for it, this one is about as far from normal on field interaction as you are ever likely to see. Taking drugs doesn't endanger an opponent (normally) but it's banned, and that's not just a performance enhancement issue it relates to recreational drugs as well.
What the storm shows isn't a lack of a sense of proportion about different kinds of dangerous play, it's what people actually think brings the game of football into disrepute. No, it's not as bad as matchfixing or certain other crimes, but there's a reason why this is on TV and in the newspapers all over the world. It's extraordinary and it has happened in the most public arena, the showcase and cash cow for FIFA.
That's why it doesn't matter if Chiellini is injured, horrified or even angry. FIFA have to ban Suarez for being an embarrassment and, because it's not the first time, they can't just ban him for a few international matches - the matches won't be important enough to fit the crime.