I know I'll upset people with my response but I've got to say it, why do people always try to find ways of getting around the intention of laws and rules? For all forest service property, the roads are closed to all motorized vehicles including ebikes, that's a federal forest service rule not a Fish, Wildlife and Parks rule.
As of March 4, 2016
See this link for the forest service policy letter from 2016.
This is the Internet, why is it so hard for people to do their own research, I guess it's just that "short cut/break the rules" mentality that's so common nowadays.
easy answer is, most humans are lazy scumbags at heart and want things easy rather then having to work for anything!