This is an approach I’ve never heard before. It is widely acknowledged that Vesuvius destroyed Pompeii in 79 AD. Your conspiracy theory is amazing because somehow the people hiding the facts about the real date found a way to get the entire tree ring history from Europe, Japan and South America to go along with their ruse. Even if Pliny the Younger did not record the event, Carbon 14 dating on bread and Argon / Argon dating on ejected lava date the catastrophe to the late first century.
Carbon 14 and Argon / Argon dating are in no way calibrated by dates in history books. They are anchored in the repeatable laws of nature. Carbon 14 date calibration is firmly anchored to indisputable tree ring and coral layer evidence. For a complete understanding of how Carbon 14 calibration works try taking a look at the Fairbanks Radio Carbon Calibration web site. The address is attached. http://radiocarbon.ldeo.columbia.edu/...arch/radiocarbon.htm
You can also look up INTCAL 2009. This is the current gold standard in R14 calibration.