Judging from the roads on the list with which I am familiar, I would say the list is accurate, even when one factors in the number of cyclists frequenting them. For example, I drive Stage Gulch (Hwy 116) twice each day and I have never seen a cyclist try to ride it. Yet it appears on the list, which leads me to believe that a high percentage of those few bike riders who are brave (or just sadly ignorant of the dangers) enough to attempt it are being injured. The list includes only "severe injuries," which makes me wonder how many minor injuries occur on these roads as well.
I'm glad someone came up with this list to warn newbies and out-of-towners of dangerous roads that experienced locals already know to avoid. I recently saw on a Kreb's map that Hwy 116 was shown as a "favorite route" for cyclists. Wro-ong! I always contact the local cycling club before venturing into the unknown. Luckily, we here in the Northbay have very helpful clubs.