Who’s talking server side code? just releasing the compiled server binary should be enough. Just like games typically are released as binaries and assets, and not as source code.
Can you decompile the server binary? Yes you can! But you can also decompile the game to work without the server or with a makeshift server. Either is just a lot of work that few people are willing to do.
Protecting the server code is rather useless if the game can be cracked, since then you can also play the game for ‘0.00 €$’.
It’s gotten to the point where many atheists appear to fanatically believe in science, but without believing in the scientific method on which science itself builds.