I know it seems a bit harsh to close the kitchen, but it seemed to be the simplest way to solve several problems related to ensuring the right atmosphere for the films. If there is a supply of food, then there will be people coming over to the kitchen to buy it. Plus people will have a non-film reason to be in the main room of the cafe. This, plus noise from the kitchen, creates distraction and people stop watching the film.
Also, we don't want volunteers talking in the kitchen - if they do then we can't expect the customers to keep quiet for the film. But, this makes it less fun to work in the kitchen, if you aren't so bothered about the film. So if the kitchen is closed, we don't need to have people working in the kitchen in silence.
I had been closing the kitchen or moving to the night menu/cakes and bagels only at 8 in November/December, so closing at 9 is an improvement.
From working the last few film nights, I have seen that if there are sources of distraction, they spread. We need to minimise these sources, so that we get enough customers who come for the film (and not just for the food). If someone comes in and sees a room full of people quietly watching the film, they are quieter too. If they come in and see people eating, talking and walking around, they will not be quiet.
It is true that the glasswasher is no longer noisy, and the coffee machine could be turned off early. But the microwaves, soup cauldrons and till all make noise too.
I was convinced that closing the kitchen was the simplest way to make people watch the films quietly. But someone might have new ideas.