As I mentioned above there are many Kosher rules.
Plates, pot and utensils that were used for non Kosher food especially if heated cannot be used by strictly observant people. Therefore, all pre prepared Kosher meals are served with disposable plates and utensils.
They can be "Koshered" and become useable by following various procedures, and that what was done by the supervising Rabbi at the Solarium Bistro. Once that was done any non-Kosher food that comes in contact with the Kitchen equipment would void the Kosher status, hence the need to close the SB to outside non kosher food.