After reading your post, I did some research on the net regarding the neurological phenomena that can occur as a result. Most people don't remember anything, but those who do often have hallucinations which, as with dreams, are based on bits of information we've garnered from elsewhere. Sometimes they are religious in nature, sometimes they are not.
I did read of a few instances where people could report things that happened in the operating room while they were in circulatory arrest. Clearly, the brain does not stop working, and the person is not dead.
As I said I am not going to speculate on this man’s vision.
However, you still don’t seem to get what I am saying. “Clearly, the brain does not stop working, and the person is not dead.” Define dead. There are no vital signs - no blood pressure, heart rate, etc. The body temp is 17 degrees Celsius. EEGs are done that show total supression of brain waves & activity. I’m not sure why you feel the brain hasn’t stopped working. We supress it to where we cannot detect activity with a bispectral index. Could the patient be dreaming? I’d say unlikely; but your assertion that they’re not “dead” is pretty much of a stretch. You have no idea what went on during this man’s surgery.