I agree with your main claim that the protests will cause more deaths than they save, but I disagree with your estimate of caused deaths by at least an order of magnitude.′
The estimated change in reproduction number is not compelling. Firstly, the largest protest in American history had attendance of 3*10^6, or one in a hundred Americans. So assuming this protest is tied for most attended in US history, and other Americans behave the same, the protestors must each have an R of 30 to bring our average R from .9 to 1.25. That is 10 times the pre-SD reproduction number. Assuming the protestors have an R of 3 or 4 seems reasonable to me. Now that we know much transmission is from speaking, 10 would be the upper limit of my 95% CI. Assuming an R of the 3, reduce the estimate to 10%
Also the protests are short relative to the time a person is contagious. I doubt the protests will maintain attendance in the millions for more than two days, which is less than people are typically contagious. Therefore their influence on our effective reproduction number will be less than you estimate. Seems like people are contagious for at least 4 days, so call that a reduction by half. So reduce the estimate by a further 50%.
So I would reduce your estimate from 75,000 to 4,000. Which is still a lot. More than my expected benefit from the protests by movement building.
I am skeptical of this line of reasoning because I see little reason to believe that malevolence determined the policies in question. Game theory political scientists argue that different institutional structures make it rational or irrational for leaders to distribute public goods or targeted goods, practice repression, allow political parties. For a more in depth treatment, see the Dictator’s Handbook by Bruce Bueno De Meqsuita and Alistair Smith. Their core argument is that because dictators must appease a very small group of powerful interest leaders (generals for Mussolini, members of the centcom for Stalin, tribal and military leaders for the Abdullah II) they can protect their power by rewarding only that small group at the expense of the masses.
Here is an illustrative example of political phenomena that is difficult to explain from the leaders personality. Torture is more common in multi-party autocracies than in one-party states. If the leaders narcissism strongly influences policies and narcissism and sadism are strongly correlated, then we would expect torture to be more common in states that ban dissent. Suppose that torture is not about satisfying the personal desire of the dictator and is instead about policing dissent. Now it makes sense that if some dissent (like resistance to a new “non-security” policy) is allowed, there must be some boundary into banned dissent. Then the occurrence of torture in multi-party states makes more sense and the rarity of torture in the most severe autocracies makes sense.
Opposing personality-of-dictator explanations to ideological explanations surprised me because it ignored the strongest explanations in institutional structures of states and in political cultures. Possibly you emphasized ideology because your samples are older. While the early modernist dictators were authentically ideological, most modern autocrats espouse a bland, centrist, syncretic corporatism. Dictators like Chavez and Castro are the exception today (although their ideology does influence behavior). Here is an article which argues most dictatorships are interest driven, not ideologically driven https://sci-hub.tw/10.1080/13510347.2017.1307823