In my experience, lane splitting is much safer. It has saved me from violent rear-end collisions on several occasions.
I'll also go as far as to say that commuting is certainly more dangerous than most recreational riding (the exception being recreational riding when the drunks are out, e.g. midnight on the weekend) due to traffic density. The text-and-drive crowd is also more active (both on their phones and on the road) during rush hour, perhaps because driving inattentively seems like a safer practice at lower speeds.
Commuting being a seemingly more dangerous activity doesn't preclude commuters from being a lower-risk-of-injury group. Age could be another factor -- older riders are more likely to be injured in motorcycle accidents, and might be less likely to commute or lane-split.
The study is crap. It lacks the data to control for other factors and draw meaningful conclusions about much of anything.
I'll also go as far as to say that commuting is certainly more dangerous than most recreational riding (the exception being recreational riding when the drunks are out, e.g. midnight on the weekend) due to traffic density. The text-and-drive crowd is also more active (both on their phones and on the road) during rush hour, perhaps because driving inattentively seems like a safer practice at lower speeds.