One great first step OpenAI can take towards this is by actually making their models open. As long as the models are intentionally kept back and intentionally profited from by already wealthy private citizens, inequality will grow, not shrink.
Not to mention that people in poor countries (which as Gates cites as the "hotspots" for inequality in health) won't be able to use some HTTP API based in US/SF. Not just that latency will kill requests, some of the places don't even have internet connectivity. How is OpenAI supposed to help those communities if the "inequality fighter GPT-4" is gate-kept behind a centralized HTTP API?