Their previous history of racist posting was pretty clearly taken into account, it wasn’t some random LOTR fan who happened to get misconstrued.
You may want to look up racist dogwhistles, and how they are used. Equating migrants to an invasion horde is a common racist dog whistle and fearmongering tactic.





















Notice that the user who received the temp ban went on to complain about it, and even after other users explained why the memes were racist (including the zuckerberg post that you also agree is racist), the user dismisses the racism entirely and just says “not arguing everyone has to like the memes.” They are showing zero ability for self-reflection and refuse to acknowledge the memes were racist.
I still would’ve given a permaban based on the evidence at hand, were it my community. You can disagree with that and give them more and more chances, but posting one blatant racist meme which is indisputably racist (even you agree), shows that we’re not working with some innocent lamb who just isn’t keeping up with modern dog-whistles.
If someone had only posted the LOTR meme without that previous history, then I would give benefit of the doubt, and just remove it and explain why.