You are talking about a vegetarian. I don't think you have particularly strong rights against people discriminating against vegetarians, unlike discrimination against gender, race, religion and so on.
Now a search warrant gives the police the right to search your house. I can't see how this would give a police officer the right to eat in your house, or to have a nap on your sofa, or to use your toilet, or to watch TV in your house. On the other hand, if he or she does, you will have a hard time doing anything meaningful about it.
On the other hand: Say a police officer comes with a search warrant that allows him to search the home of a devout muslim for suspected illegal drugs. The police officer demonstratively eats a bacon sandwich in the muslim's home, then finds a significant amount of illegal drugs.
A defense lawyer would have a field day with this. The bacon sandwich eaten in the house of a muslim would be a clear sign of racism (I suspect that police officers very rarely eat bacon sandwiches while they perform a search), and therefore there would be reasonable doubt that the drugs were in the house before the police officer started the search.