Gruber went from the naively wrong claim that it would insert secret hidden characters (which would be trivial to remove, obviously), to quickly writing a giant essay as if he's an expert on LLMs. Like you said, he is strangely fixated on the EU, and is certain any EU rule is the worst thing in the universe, and this whole piece seems motivated by that guiding force.

Further he later compares Gemini to Anthropic models, saying the latter "writes better", emptily ascribing this to the synthid stuff. I think he heard that Anthropic currently has superior models, but it certainly isn't because they "write better", and if anything Opus 5 now is virtually unintelligible, before the fingerprinting.

The fingerprinting stuff sounds weird. If the EU wants it, it should be limited to the EU, and Anthropic is fully capable of doing that but clearly saw value in recognizing their own output. Is it going to destroy the quality of the output? We'll have to see, and this anti-EU piece, predicated on utter ignorance of the field, is not convincing.