The issue seems to be a jet fuel like substance in the intake manifold. According to Waltrip, that was done by an unknown individual on the team. Not done by Toyota.
But Toyota should have known there would be a double standard. If the same incident would have happened with another manufacturer, no one would be blaming the manufacturer. But since it was Toyota, the floodgates open.
Besides, the reason why a lot of true car enthusiasts don't like NASCAR is cause the sport is so homogenous. EVERYTHING has to be the same on all cars. How boring is that? Then all they do is drive around in a damn circle. So what do they do? They go out of their way to pick on things like rivet holes in wheelwells or missing pieces of tape.
My suggestion to NASCAR: If you're so bent on homogenous race cars, why not just get rid of all manufacturers altogether and just have a standard body and a standard engine? That way, you can cash in on all the licensing as well.