It's quite an interesting insight into what kind of thing Musk himself feels is a great insult (hence he is susceptible to it) as well as how much Musk thinks his opinion counts for people such as the Polish Minister of Foreign Affairs, all of which dovetails with the idea that the guy suffers from both Megalomania and Narcisistic Personality Disorder.

For any reasonably well adjusted person in a position of responsability such as being the Foreign Minister of a country the size of Poland (or, frankly, for anybody self-aware and self-confident), being called "small man" by somebody like Elon Musk is roughly the equivalent in importance to being barked at by a dog that cannot actually harm you.