"Slander is not criticism. "
The very same argument is used by oppressive governments all over the world.
Every tyrant who is opposed to the freedom of free speech argues the very
same way in order to defend his actions. Please think about that.
"You make it sound like it's hard to sue another EU citizen. It's really
not."
If you don't know his name or address, then it is. But even if you did I
would still sleep very well since there is no law that keeps me from calling
your actions "unethical" or offensive.