> The left hemisphere actively confabulates, inventing plausible explanations for actions it didn’t initiate, suggesting that much of human self-narrative may be post-hoc storytelling.

Sounds like the left hemisphere usually uses something from the right hemisphere to answer those questions and it can't do that if it's been cut off?

We know that our brains are capable of hallucinating due to substances (drugs), being asleep, brain damage (including split brain), hypnosis, etc. Just as RAM damage make your computer do weird shit. That doesn't mean it operates that way normally.

You can't just remove a huge part of a system and then assume that the whole system behaves the same.

Indeed. People literally make stuff up when their corpus callosum is severed.