He has also denied this as well. In fact the whole point of saying that he had never bought, sold, seen oil...etc is that he could only do it with vouchers.
Say, didja happen to catch his testimoney re Zuriekat?
I don't think your "he also denied" as if implying a flat denial really is accurate.
I don't know the man, and I certainly haven't reviewed the evidence against him nor am I competent to evaluate it's authenticity.
But just academically, if you had a gift certificate for a $25 steak dinner at Texas Roadhouse, and I bought the gift certificate from you for $10, could you not say "I haven't sold one ounce of steak, and nobody bought one ounce of steak from me."?