Fair enough, I appreciate the response. Just note in this case I think the precedent should not be private company can ignore public demand. If they can unilaterally ignore the demands of the Saudi government then why not any liberal government? If you operate in a country you should have to follow their rules. If the rules themselves are bad that is a different question.
The remedy in that case then would not be a tax but to ban them from operating in that country. We already have these sorts of export controls with other countries. It is just the case that despite their egregious human rights record (bone saw, anyone?) the United States has propped up the Saudi regime since basically it first came to exist roughly a century ago.
The reason is obvious - Saudi brutality is a feature not a bug. It secures access to cheap oil.
The export control angle is interesting. I was treating addiction, radicalization, capitulation to authoritarian govts, abetting human rights violations, productivity loss, etc., as the symptom of a common cause: the hyper-optimized engagement model and curbing it with a policy. You're right that some of these harms might warrant categorical exclusions rather than pricing the whole business model out.
I may have had an overly optimistic ideal of people running small federated mastodon servers for friends and family for free/donations being the only type of "social media".