Getty died this week at the age of 84.
"They would certainly have been welcome. I don't know why they wouldn't be attending mom's funeral. Maybe it's a painful thing," he said. "If it was someone I'd been tight with like that and worked with all those years I'd have been there."
Gettleman said Tony Thomas, a former executive producer of "The Golden Girls," did attend the funeral.
Arthur, who played Getty's daughter on the show, told "Inside Edition," it was too difficult for her to deal with the emotion of a funeral.
"She's been out of it so many years, not recognizing anyone. It's a godsend. She's at peace," Arthur said.
McClanahan, who is living in New York, told the entertainment news program she couldn't attend the funeral because she recently had surgery.
"I'd like them to know that I didn't (attend the funeral) because I can't fly right now with knee surgery. I don't know why Betty and Bea didn't go, maybe because they, too, have said their goodbyes to her when she was alive," McClanahan said.