You're just proving my point. Why would the EU want Greece and Cyprus for membership? They neither posed a threat nor constituted serious competition.
So of course the EU had to be 'bribed' to accept Greece, and then Cyprus. The EU knew it would become liable for protecting these two against Turkey and it was an expense they preferred Greece and Cyprus to manage on their own. So Greece and Cyprus had to offer cash incentives to receive EU defence.
However, Greece's oil reserves were known since before the 70s. So Greece was allowed in with all the conditions we have seen enacted - open access to their funds and assets.
Once Cyprus' hydrocarbon reserves were established (before they became common knowledge) then Cyprus was allowed in with only the haggling for how much the EU was going to benefit financially.
(The UK opposed Cyprus' entry because - among other things - they did not stand to benefit much personally from Cyprus joining the Eurozone.)
Turkey would have carried out ALL its threats against the RoC's explorations if Cyprus was not already receiving the protection from the EU as a contributing member to the coffers!