> Being able to prove a fascist dictator who was killing people for being gay, was secretly engaging in gay acts themselves, might help your cause of protecting gay people.
Because the DKIM keys were not made public, and a message sent from their account could be confirmed to be authentic.
If the keys were public, they could claim forgery. Regardless they could claim their account was hacked, but they couldn't deny the message was sent from their account.
I'm not asking how the technical mechanism proves the messages may be legitimate. I'm asking how you could use that knowledge in the specific situation you outlined to accomplish anything productive.
How?