Having spoken to the hotel staff the position regarding the resturant is that it shut for evening meals from the 30th September. During the summer period only two couples, apparently, booked for half board with Olympic. The second couple, unfortunately for them, arrived on the 30th, as did we!! All the Nireus was able to do was to make an arrangement with a local restaurant to feed the guests.
I hope this answers your question. Have a great hoidy, I'm sure you will; it is Symi after all!