Why would anyone put out-of-shape Joe Don Baker in an action hero movie?

It's amazing Greydon Clark chose fat Joe Don Baker to be the lead in his action hero movie. They even make it a point several times that he's fat with digestive problems. How is that appealing in the age of Arnold Schwarzenegger and Sylvester Stallone. I can only imagine several dozens of actors turned down the part before Joe Don was offered it.

What's really hilarious is when asked what he thought about MST3K doing his other movie "Mitchell," Joe Don threatened to do physical violence on those guys if he ever met them.