I don't understand how he could get such a warning in VA, as long as he sold it to another legal VA resident and logged all info in his bound book (unless BATFE agent is FOS, totally possible). He could not lose his C&R for selling to non-collectors, unless his book indicated that he is abusing his license for profit versus improving his collection. I've sold C&R rifles and a C&R handgun that I didn't need for my collection any more (got better ones). The individuals I sold them to are VA residents and can lawfully own them here. What they do with them is their business.
I can't understand that one either. As long as the sale is legal then he is in the right. They would not have done what was said unless there was alot more to the transaction or story and even then he would be lucky to get a warning.