Does that make him an accessory to fraud?
Probably only if he actively participated, unless either CA of the feds have a law requiring people to report known fraudsters.
But this isn't just your neighbor's lawn care guy talking, this is an elected official, part of the state government, the President Pro Temp of the state senate. The photo appears to show him taking his oath of office. I'd really like to know what that oath says, because I'll bet a Starbucks latte that he's not living up to it.
[Edit to add]And here it is:
http://www.dcaboardmembers.ca.gov/member_info/oath.pdf[Edited to correct the typo Fisty observed]