"Boards have a fiduciary duty to the shareholders."
Xi and the CCP/Chinese Government make a bid to buy Google, for a 20% premium.
They also bid to buy Twitter, Facebook and Microsoft. All for 20% premium.
Should shareholders do 'the right thing' and sell?
Assuming you're not a Twitter shareholder why do you care about investors interests? Why don't you care about your interests?
Why do plebes constantly argue against their own interests?
As a Twitter user, I pretty much don't want Elon Musk involved, and I don't really care too much otherwise.
Every organization has stakeholders: customers, suppliers, financiers (investors and debtors), execs, employees.
If a Union forms, they can take considerable control away from investors.
If debtors come calling, they can take considerable control, away from investors.
'Externalizations' such as issues in the public good, or environmental issues - matter.
Usually, we like to think of those things, in the context of a 'Charter' that highlights those things i.e. some 'Crown/Gov. Corporations', things like the CBC, US Post etc..
When you say 'things that don't matter vs. things that do' - that could be true, or only even true from a certain perspective.
For example, you might think they should not focus on moderation, but instead, advertising. Well, without appropriate moderation, the ship could sink. Also, issues like moderation can be hard and ultimately satisfy nobody, and frankly, might not even be an operational distraction (although it probably is).
Finally - as property of Elon Musk - Twitter will be literally whatever he wants it to be.
Rich People have, throughout history, bought newspapers etc. for the entire purpose of slandering their opponents. The news wasn't even 'real' until just a few generations ago, it was all tabloid.
Elon Musk could will likely censor those who disagree with him and his colleagues, and boost/amplify those who's interests are aligned with him - maybe not as badly as others, but it could be that.
If you're going to take a 'principled stand' on this issue, it's going to have to be one probably of the externalized common good, not so much shareholders.