Could the letter have been written by a thirsty adult?

I concur. I think it is telling that he didn’t choose to just stonewall the reporter with “No further comment.” He has a malevolent drive to push that narrative

I am sad that I am ok with a strong advocate for values I do not hold, ending up murdered.

Values are not universally valid.

The values held by this dead person were harming society by the theft and denial of human rights for others.