"A forgery? That makes it sound like he made it to pull a scam. It is a COPY. Big difference."
Nah. He was pulling a scam right out of a Donald Westlake story. According to the article;
"Experts said Trachte probably made the copy in about 1973, when he and his wife were going through a bitter divorce. The settlement let him keep the Rockwell."
He did the paint-by-number version with the intent of defrauding an ex. Didn't need to, but could have. Anyone remember the Dortmunder story where the forged object was a statue and Dormunder has to steal it to keep the ex from realizing she had been shuffled the forgery?
Anyway, this is kind of a semantical game now. It's a copy, and perhaps was intended as a forgery. Fine.