Hello Archon. Of course, the language is not appropriate, but it isn't worth the effort to report it to the Support. Just blacklist the player so he cannot send you any message at all.   I have been playing this game for almost 12 years, so as a player, I dare to suggest that if he is a very strong player and you are not so strong,  consider solving the issue via diplomacy. If you are strong, just ignore him. The vacant slots are free to be claimed, but we shouldn't expect fairness in a wargame where only the power rules, as it is in the real world.