This concern (that a profit-maximizing CEO like Sam is not the type of person who should decide the ethical fate of humanity) was and is the whole point of having a non-profit as the owner of the for-profit tech company, so that ethically-driven people who value human well-being over growth can be in charge of the non-profit board and exercise final say over the AI's ethical constraints.
The fact that Microsoft now has a board observer seat seems highly corrupting, and contrary to the board's fiduciary purpose. This is discussed here: https://news.ycombinator.com/item?id=38471990 Basically, Microsoft now has an enormous, and indecent, insider information advantage (allowing them to conduct software development industry market front-running, which would be illegal but it will be impossible to prove that the source of their ideas is the "forbidden fruit" of what they hear in board meetings). Details may be found in that link.