If that were true, then quadriplegics would have cognitive issues, as would those who have their vagus nerve severed. Those people don't suffer from impaired cognition or drastic personality changes, so we can be sure that the nerves in the gut are not important for brain emulation.

Also human brains have an average of 86 billion neurons, so emulating an extra 100 million cells (0.1%) would be trivial in comparison.