Either he really was the wrong person to lead openai, or the exact right person but the board couldn’t go along with his view for ethical or financial reasons.
My guess is he's the right person to run closedai, but not openai. Board has no financial interest in the company, and wanted to stay true to its initial goal.
You would need work authorization to take on paid internships - and there's almost certainly no work authorization option available. There have been and will be changes to the J-1 program so depending on your area of expertise and background, the J-1 might be an option but there would be complications with this if your plan is to remain in the U.S. after the J-1 internship.