Well, it turns out that you can indeed fry burgers in your rice cooker, if you turn the rice cooker on High.
The problem is that they end up sort of steamed as well as fried, and so the texture is odd. Also, unless you have a huge rice cooker, the burger ends up sitting pretty deep in its own grease. So yeah, I think the folks who suggested that strong spices be mixed into your burger before cooking were planning to cover up the weird texture that way.
If you really want to descend into rice cooker madness, here’s a recipe for Oreo Rice Pudding. I’m torn between thinking that it could be good, and thinking that it looks like Cthulhu’s birthday party.