I know a small mom and pop shop in San Pedro, CA that got the same letter about when this guy did.  EPA was demanding $200K from them even though when you bought their products; they were listed for off road use only and you had to sign that that was how they will be used.  EPA didn't give two shits!!  They had to get a specialized lawyer as well.  Might be the same one this guy is using.  Not sure where it's at.