Comment by Certhas

Compare:

"O3 performs spectacularly on a very hard dataset that was independently developed and that OpenAI does not have access to."

"O3 performs spectacularly on a very hard dataset that was developed for OpenAI and that only OpenAI has access to."

Or let's put it another way: If what they care about is benchmark integrity, what reason would they have for demanding access to the benchmark dataset and hiding the fact that they finance it? The obvious thing to do if integrity is your goal is to fund it, declare that you will not touch it, and be transparent about it.