If Twitter/X were to hire a rep in Brazil, regardless of the title they're given, that rep would have little to no power over the moderation choices of the parent company.
Musk could choose to furnish the Brazil office of Twitter/X with the necessary resources to do content moderation to conform with local law. He chooses not to, with predictable consequences in terms of legal liability for any local representative.
Which is kind of weird and illegal in many countries, but in the US it is almost the norm.
Also no, chairman isn’t only accountable to themselves. Where did you read that? Investor having seats on board is so they can have a voice in the direction of the business.
Activists investors often try to have a minority stake and a board member so they can force changes at the company -[0]. A recent example is Elliott’s effort at Southwest Airlines -[1]
[0] - https://www.investopedia.com/terms/a/activist-investor.asp
[1] - https://www.reuters.com/business/aerospace-defense/elliott-b...
Not sure why you include investors all of a sudden, as I didn't mention about that. I have no issue with shareholders having a seat on the board.