There is no absolute right of free speech in the EU (and probably most countries); foreign companies operating there are subject to local laws when doing so.
(In my non-EU country that tweet could be interpreted as a hate crime too, quite uncontroversially)
I'm not as familiar with EU laws, but if I posted this joke online in the UK, then yes, it could easily be considered "grossly offensive" and therefore would be illegal.
I won't say it happens particularly often, but we do charge people in the UK for posting offensive jokes. Hell, you can be charged for saying something factually true if it's offensive in the UK.
Sure, but can this joke itself be illegal? What law forbids a joke like this? It's not calling for violence, it's not denying the holocaust (just the opposite), it's just.. well.. a joke.
Even the EU is going to have some legal standards around this sort of thing, or you could spin whatever you want into being some sort of coded language for something that is illegal. I'm unfamiliar with EU (or Germany as it may be?) standards, but using the US as an example, there's the Miller Test [1] for determining obscenity. It has three parts:
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1) Whether "the average person, applying contemporary community standards", would find that the work, taken as a whole, appeals to the prurient interest
2) Whether the work depicts or describes, in a patently offensive way, sexual conduct or excretory functions specifically defined by applicable state law
3) Whether the work, taken as a whole, lacks serious literary, artistic, political, or scientific value.
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Something can only be deemed obscene if it meets all 3 criteria, which courts tend to interpret pretty rigidly. For instance, an average person is not the most sensitive or politically correct person. Of course it also somewhat amusingly emphasizes the cultural differences. Creative use of a nipple and some mayonnaise might be deemed as obscenity, while a graphic decapitation could not.