Not sure where the joke is supposed to be.
From wiki....
In 1996, Gruenwald succumbed to a heart attack, the result of an unsuspected congenital heart defect. Gruenwald was a well-known practical joker, and due to his young age, many of his friends and co-workers initially believed the reports of his death to be just another joke. Just days prior, he had done one of his trademark cartwheels down the halls of the Bullpen. A longtime lover of comics, Gruenwald made it known amongst his friends and families that his one desire was to have his ashes used in part of a comic. In accordance with his request, he was cremated, and his ashes were mixed with the ink used to print the first printing of the trade paperback compilation of Squadron Supreme.[22]
https://www.newscientist.com/article/mg14619713-300-no-funny-business-when-cartoons-are-signed-with-dna/