The article doesn’t state what the dating method was. The usual dating methods are estimates and not precise. I’m not sure they have the resolution to change the estimated date by the relatively small amount of several decades.
I’ve been to Santorini 3 times and it’s truly worth the visit. One can read Charle’s Pellegrino’s “Unearthing Atlantis” to get more background on Santorini and the volcanic explosion.
Thanks KamperKen. The dating method used was radiocarbon dating, which ordinarily is a good one to use for the <50,000 year old organic material, but on Santorini the uptake of "dead carbon", C12, into biological systems growing in the soil there makes dated items appear older than they are.
C ratios: for example, plants on the Greek island of Santorini, near the volcano, have apparent ages of up to a thousand years.
wikipedia
search also for "Evidence for magmatic carbon bias in 14C dating of the Taupo and other major eruptions".
The olive-branch dating of the Santorini eruption March 2014