I really am not expecting Apple or Microsoft to discover AGI and ferret it away for profitability purposes. Strictly speaking, I don't think superhuman intelligence even exists in the domain of text generation.
Of course, I agree that Stability AI made Stable Diffusion freely available and they're worth orders of magnitude less than OpenAI. To the point they're struggling to keep the lights on.
But it doesn't necessarily make that much difference whether you openly share the inner technical details. When you've got a motivated and well financed competitor, merely demonstrating a given feature is possible, showing the output and performance and price, might be enough.
If OpenAI adds a feature, who's to say Google and Facebook can't match it even though they can't access the code?