Well the one thing right in your post is that it is true, you are never going to walk into a restaurant and say "I would like tuna sushi" and get tuna fried rice, because that isn't what "sushi" is referring to.
"Sushi" means rice in so much as it is referring to the fact that sushi is raw fish with rice as compared to sashimi which is without rice. You will never find a restaurant in Japan that serves anything thing but raw fish served in or in vinegared rice if you order tuna sushi, and you will also find that you will never be served only raw tuna without rice if you order tuna sushi. This is true in the US too.
The problem stems from the fact in America we don't eat just raw fish without rice, so there was never any need to import the word sashimi so in the minds of English speakers "Sushi" referred to the raw fish part of raw fish and rice, compared to the Japanese meaning which means sashimi with rice.
In conclusion, I think starting poster of this treads pedantic point was that saying sushi is dangerous is just silly, since it isn't raw fish with rice that is dangerous, it is raw fish. Therefore why focus on the fish with rice part by using the word Sushi. It is like if there was an outbreak of mad cow disease and a study saying "Hamburgers Dangerous" while that is true, would it not be more help to say "Beef Dangerous" since there is nothing about a bun, lettuce, and a tomato that would make hamburgers more dangerous than just eating a beef paddy.