Why no one wanted to buy the Green Shipping Fuel

Basically yes:

In the forseeable future, renewable e-methanol will be substantially more expensive than conventional oil-based shipping fuels like marine diesel or LSFO.

But lets not forget the lobbying against any sort of regulation on it like forcing a quota on renewable fuel sources.

Even lobbying organizations from the shipping industry appeared positive towards such a quota. In a statement by the European Community Shipowners' Associations, they write that they support the EU Parliament's proposal for a 2030 quota in principle but want similar requirements for fuel suppliers.

they support it in principle... what the hell does that mean? They like the idea of it but cannot actually support it? Or just they want to sound like they support it when really they don't. Either way the proposals were watered down and delayed:

If any of these proposals had been passed, the fate of FlagshipONE might have been different. However, the EU eventually agreed to much weaker requirements. A quota of 2 percent RFNBOs would only start in 2034, and even that comes with some caveats. Under the final FuelEU Maritime regulation, shipping companies would not have any requirement to purchase relatively expensive e-fuels for another decade and can likely fulfill the modest emission reduction requirements while still primarily relying on fossil fuels.