I for one do not think lane splitting is more dangerous if done at reasonable speed. I live here in California and split all the time when necessary. No problems yet...been very close to being rear ended when flowing with traffic though.
I 100% agree, and I too lane-split for miles at a time on both mountain roads (Hwy 17 in Santa Cruz) and freeways in Silicon Valley when commute traffic is slowed or stopped. I've seen people do it wrong and watched them launched over a car hood (OK, I only saw that once, but it made an impression), but I appreciate both the ability to get out of tangled traffic and of not being at risk of getting rear ended. In a manner I view it a bit like speeding. If you launch a study I bet you'll "conclude" that speeding increases accidents. But I find judicious use of speed also provides separation and in many cases makes me feel safer.
Also note that the study didn't conclude what you may think. It doesn't show that lane-filtering caused more accidents or those accidents happen while the cyclist was filtering. It showed that when they changed the rule to allow filtering, reported accidents went up. Was it because there were more motorcyclists on those roads trying out the filtering, could it be because that area was being studied there was more attention to making a record of the accidents, were motorists oblivious that filtering was allowed in that section and not looking for a motorcycle beside them? No idea, because the study didn't go to that depth.