Yes and no. It was the pinnacle in a series of bizzare behaviour from Tony while he was the Prime Minister. Certainly its the one people most remember of him. Keep in mind he ate it with the skin on as well. I think its also something people look out for, with the previous PM Kevin Rudd being somewhat infamous for eating his own ear wax on live TV.
When I was working on an archive project for the ABC, "tony eating onion" or some variation was the most common thing people searched for in the system when they first started using it.
More bizarre was that time he froze and didn't speak for 30 seconds when asked a difficult question by a reporter about his "shit happens" comment. Justin Trudeau did the same thing recently when asked a question regarding Trump.
When I was working on an archive project for the ABC, "tony eating onion" or some variation was the most common thing people searched for in the system when they first started using it.