I assume this is a joke as don't see any manipulation. In fact, it's quite simply worded and looks more like one of those logic problems where 'only 53% of people like pineapple on their pizza, while more than four in ten don't' is part of the set up where you have to work out what flavour pizza Sam chose and who had the four cheese one, which wasn't Ahmed.
Their biggest offence is quoting a You Gov poll. 'You Gov' sounds trustworthy, but you only have to read the questions to learn that it's complete nonsense, impossible to answer any questions definitively, not that most people will be interested as they're only zipping though the questions for the points and vouchers anyway.
I agree with the restaurant's stance. It's an abomination what many places put on pizza in this country. When I rule the world, no more than 20% of the pizzas on any menu will include processed meat. Chicken, sweetcorn and pineapple will all be banned.