From what I understand, there are two ways the government approaches fining individuals (with respect to vehicle fuel/emissions). The first is the old "Red Diesel" fine where the DOT can impose a fine for running fuel that has not been properly taxed. I think that is a $10,000 per day fine. The other is the EPA/DEQ fine for violating the emissions requirements of your vehicle. So if adding 2 Cycle oil to your Diesel fuel creates a violation of your emissions then yes, you could be fined. Since the 2 cycle oil has been properly taxed (assuming you bought it at the store) then the DOT defiantly has no claim. As to weather burning 2 cycle oil in a Diesel vehicle creates "illegal" emissions, I'm not really sure. I can see many ways to argue both sides of this issue.
Ron