When the car surfaces and can be verified as real it can be said to exist. In the almost 30 years since Super Chevy published the ZL-1 VIN list not one anomaly has been noted. The ZL-1 that was shipped to Canada is on the list, still exists and is not yellow. How convenient to claim this one just wasn't on the list.
When GM of Canada started the documentation service many years ago they sent a copy of the page your car was on along with 19 others. Some guys caught on to this and began requesting other VINs just to acquire pages. A few people claim to have all of them. Lots of other COPOs but no more ZL-1s.
Don't be so gullible.