It really feels like the reason this is being released now and not months ago is that that's how long it took them to figure out the convoluted combination of different evaluation procedures to beat GPT-4 on the various benchmarks.

Why is that misleading? It shows Gemini with CoT is the best known combination of prompt and LLM on MMLU.

They simply compare the prompting strategies that work best with each model. Otherwise it would be just a comparison of their response to specific prompt engineering.

The places where they use the same methodology seem within the error bars of the cherry picked benchmarks they selected. Maybe for some tasks it's roughly comparable to GPT4 (still a major accomplishment for Google to come close to closing the gap for the current generation of models), but this looks like someone had the goal of showing Gemini beating GPT4 in most areas and worked back from there to figure out how to get there.