Why wouldn't I trust someone who took action to uphold their organizational charter, knowing there would be intense pressure to do otherwise?

Investment is only partially about trust. I agree Sam's a pretty investable guy. I expect Sam to pursue growth through fundraising, product commercialization, corporate partnerships, etc in exactly the YC mode. He's also clearly ok with letting the momentum of that growth overwhelm the original stated aims of OpenAI, especially given what the original firing press release said about Sam not being entirely forthright. I suspect Microsoft made their investment knowing that something like this might happen. It's not trustworthy that he tried to overwhelm nonprofit aims under for-profit momentum, but if you're an investor do you care?