Israel is an ethnostate because they are deliberately ethnically homogenous and view Arabs as inferior on an institutional scale, not because of their state religion. A state with a religious ruling class is called a theocracy.
I see what you're saying because religion has societal and cultural impacts that reinforce specific behaviours, but not all states that have a state religion are actually theocracies in the traditional sense.
I dunno, maybe if you never put it up again. But you could also think of it as a performance where the act of putting up and taking down the banana is part of the art. And the person who "owns" it gets to be part of that, which is special.