Unfortunately, his delusions of grandeur didn't exactly endear him to his more experienced fellow crooks, whom he dismissed as if they were beneath him. Well..........
Simon merited one more appearance, and was never used again. When Filmation gained a new license for Batman in 1977, they opted to create new characters all over again, since this time the rights to the classic villains were split with Hanna-Barbera, though the likes of the Riddler wouldn't return for another year and a half.
Today, Simon would probably be posited as an opponent of healthy eating.