I suppose there is some correlation there, but stating it like that makes it sound like causation since there is a causal relationship between deaths and the other two things presented in the same statement.
That's the important bit to remember for a lot of these motorcycle statistics - so a squid with no gear might think "whatever man, I took the motorcycle safety course and I wear a helmet! I can lane at a delta of 40mph no problem!" Rather, all of those things combined (helmet wearing certificate-bearing registered-bike-owning) are the traits of a safe rider anyway, not necessarily the things that cause them to be a safe rider.
That was the understanding I had, that not being in the group of people who do those types of things is what lowers your risk. But all of this is inferred by "what we know about the people who died" which as the article alludes to, is not a perfect measure.