Anderson on The Kurt Angle Show said that he feels his past attitude is what has prevented him from going back.

"I'm not surprised," Anderson said. "Like we talked about earlier, I said some really s****y things on the way out the door. I completely get it. I would like to, eventually, be able to go back there and finish it out, but I completely understand if that doesn't happen. I did it to myself."

That said, Anderson did reveal there was at least one overture from WWE for a one-off appearance years ago, made by Shawn Daivari, with whom he helped found The Academy wrestling school in Minnesota, along with Arik Cannon, Molly Holly, and Daivari's brother Ari Daivari. That time, however, it was Anderson who was ready to say no.

"I was asked a few years ago, it wasn't official, but I was asked by Daivari 'Hey, you're name came up for the Royal Rumble. Would you be interested?'" Anderson said. "And I wasn't. I was just in a...I was completely out of shape. And I turned it down. But it wasn't like an official ask anyway. I just wasn't interested."

https://www.wrestlinginc.com/1286090/ken-anderson-turn-down-wwe-royal-rumble/