Neolithic facsimile to the classic Greek letters

A ceramic fragment of 7,000-6,500 years ago is bearing the facsimile to the classic Greek letters Alpha, Epsilon and Delta in a row. It cames from the Cave of Cyclope at the desert islet Youra (Northern Sporades, Greece).
This find proves that the classic Greek alphabet is older than the Greek linear alphabets. It also disprove the theory that Greek alphabet derived from the Phoenicians one, which is 3,500 years younger than the Cave of Cyclope incised potsherds.
The discovery of this ceramic fragment of of Neolithic pot (5000-4500 BC) was conducted by the distinguished archaeologist Adamantios Sampson, supervisor of the Inspectorate for Prehistoric and Classical Antiquities of the Cyclades.
In a publication on the Cave of Cyclope deposit professor Sampson reported that: "The Neolithic material was enriched with the unexpected recovery of a small-sized sherd from a coarse close-shaped vase bearing incised unidentifiable symbols. It is possible that it echoes evidence on an Aegean Neolithic 'script' or 'proto-script', a very fashionable subject of discussion in Greece, after similar finds in Kastoria lake, East Macedonia".
Who, in Greece, was writing in Greek more than 3,000 years before the mythological "Greek speakers" supposedly migrated into this land?

References:

Sampson A., The Greek Neolithical Civilization, Goulandris Foundation, 1996.
Sampson A., Cave of Cyclope, Youra, Alonnessos, Ministry of Culture, 2000