I can see an "inadvertent" registration at the BMV, probably getting an OH driver's license and wasn't listening and registered to vote at the same time.
I can't. Motor voter or not, the guy is a former police officer and a (now) former multi-term legislator. It's his responsibility to know and follow the laws. I don't accept that anyone with an IQ higher than the temperature of an ice cube can "accidentally" register to vote in a state thousands of miles from his "home."
Aside from the voter registration, though, he knew (or should have known) that once he sold his home in WA, moved to living most of the time in OH, and obtained an OH driver's license that he was no longer a resident of WA and thus not entitled to be a WA legislator.
I went through the exact scenario, on a slightly more local scale, over 30 years ago. I was chairman of my town's planning and zoning commission. I got married, and my new wife and I bought a condo in another town. My new residence was not far from my old home town, and my parents still lived in the same house they had always lived in, but there was no question that I wasn't a resident any longer, so I resigned.
This dude is scumbag. I hope he is required to pay back his salary since August.