OpenAI does not make money from math papers LOL they just release them for the sake of community. (Because sitting on those results would be considered worse.)
OTOH a marginal value of a single paper in a paper dump is basically zero. Nobody gives a flying fuck if they made 100 or 200 papers. It won't give them even a single customer. If they released, say, 5 paper per month it would generate a buzz but not as much backlash from mathematicians.