This can't be true. The 'arts & crossaint' crowd deemed Norman Rockwell an 'illustrator' years ago, therefore, it couldn't be a 'painting', but merely an 'illustration'. ~gag~
Just saw an exhibit about him at our local high school, New Rochelle HS. We can claim him as one of our own as he lived and had studios here for many years.
I remember reading that he did not object to being called an illustrator rather than a painter. I'm not sure about the "technical" aspects or differences, but I don't think he cared enough about his detractors to let them bother him.
I wish I could illustrate that well.