Dan ,Thanks for making it easy for us short bus guys .According to this:
38601. A person shall not operate, or allow a passenger in, a recreational
off-highway vehicle unless the person and the passenger are wearing safety
helmets meeting the requirements established for motorcycles and motorized
bicycles pursuant to Section 27802.
The regulations shall include, but are not limited to, the requirements imposed by Federal Motor Vehicle Safety Standard No. 218 (49 C.F.R. Sec. 571.218) and may include compliance with that federal standard by incorporation of its requirements by reference.
That Simpson meets the standard by my analysis.