That is absolutely not what the split brain experiment reveals. Why would you take results received from observing the behavior of a highly damaged brain, and use them to predict the behavior of a healthy brain? Stop spreading misinformation.
It is known that the narrative part of the brain is separate from the decision taking brain. If someone asks you, in a very convincing, persuasive way, why you did something a year ago and you can't clearly remember you did, it can happen that you become positive that you did so anyway. And then the mind just hallucinates a reason. That's a trait of brains.
Yes brains can hallucinate reasons, doesn't mean they always do. If all reasons given were hallucinations then introspection would be impossible, but clearly introspection do help people.
There is no misinformation in what I wrote.