The main gripe on Facebook was that the beds that they had been using on previous days had been reserved and they were asked to move, not the fact that they didn't like her eating an orange.
The thing is, the businesses concerned actually rent that section of the beach so to all intents and purposes, those sunbeds and umbrellas are simply an extension of their businesses.
If you think of them as a table in a restaurant, you wouldn't assume that you could sit at your favourite table each night just by virtue of the fact that you'd sat there every night previously - you'd reserve it beforehand if you were really that bothered. And for the original poster of the complaint on Facebook to say that it had ruined her holiday, and wouldn't be returning, is I think, a bit over the top. Just my opinion.