Without addressing the issue of whether suppressors should or should not be legal, I'm afraid that there's a weakness in your logic. If there are very few people with suppressors on their guns, the fact that very few people are killed by guns with suppressors does not add any support to the argument for allowing suppressors. Look at the number of people in the US killed by being bitten by their per cobra. Very, very, very few. But a large part of that is that very, very, very few people have pet cobras, so that fact that very few people are killed by pet cobras does not support an argument that pet cobras are a safe pet to have.
Again, I'm not arguing for or against allowing suppressors, just pointing out a flaw in the logic.