You should probably view this as a symbolic gesture, mildly targeted for internal consumption. The Greek government doesn't view the Libya-Turkey MOU as legal or binding, so - in combination with other diplomatic actions - wanted to get on record on this (and also try to lock support on the matter at hand in case the current Libyan government is ousted).
This is mostly looking inwards though, to provide a juxtaposition of the new ND government and the old SYRIZA one (as far as foreign policy actions are concerned). Not much substance here.