What is the appropriate response to someone who says that the name "Fatima" is old-fashioned and Bedouin?

The fact that the name "Fatima" was common among Bedouins or in ancient times does not make it flawed. It is a popular name in the current era. It is the name of the Prophet's daughter (peace be upon him) and the wife of the Commander of the Faithful Ali (may Allah be pleased with him). Naming children after righteous individuals is desirable, as the Prophet (peace be upon him) said: "They used to name [their children] after their prophets and their righteous ones." The wisdom behind this is that when a child grows up and reads the biography of the Prophet or the righteous Imam, they are influenced by them and take them as a role model. The best names after the names of the Prophets are the names of the Companions (may Allah be pleased with them); reading their biographies encourages emulation of them and serves as an entry point for good.