True Dan, but as you are fond of saying, "Don't read into the rule book what isn't there" or words like that.
The passage says " Vehicles using a hybrid POWER (my emphasis) source, such as a gasoline/battery pack, will compete in the equivalent cubic inch class of the gasoline engine." Goes on to talk about the battery pack being sealed and it can't be charged separately or off site etc. Indeed the generators/electric motors are functioning as the "transmission" as has been pointed out- and transmissions are "free, ie unregulated" in all classes.
But as you say, Simspeed better get a formal special construction ruling about this drive train before going beyond computer speeds and horsepower- which of course are a lot of fun and easier to obtain than real ones...…….. Cheaper than building it and have it called illegal.