Same here. I mean, one of the two biographies I read in recent months had recounted this as "After AW's death, Frederick tried to mollify his brother Heinrich". That's... one way of describing this letter, biographer.

BTW: this further proves the genius of my guy Goethe in making Carl August have dinner with Heinrich as a method of dissuading Carl August from joining Fritz' most recent war effort without saying that this was what he was doing.