Well, in the DM's defence, Dagman did say that he had stopped playing in the campaign months before his character's death.
I agree that, if someone can't make it to a playing session or two, then their PC should get a pass.
But if someone drops out of a campaign, they can hardly fault the DM for treating their former player character like any other NPC.
To not do so would be unfair to the active players. Why should a former player's character be treated as invulnerable and untouchable, when their characters aren't?
Maybe because he never did it to anyone else?
In that campaign there were many characters that were "written in" and "written out" as time passed (his campaign started in EQ2 in 1982. I left it in late 1985. Many players had come and gone over the years). He could have simply "written out" my character in a non-lethal way as he had for others who had left the campaign. I was forced to leave because of a schedule conflict with his game and my work, as I enjoyed playing with everyone there. But life happens. And because of my knack for survival in his campaigns had gained some notability within the Chaosium HQ, where everyone else had had at least one character die in one of his games, I had become something of a thorn in the side of his rep as a GM.
He had wanted to kill off one of my characters for some time, yet was unable to do so while following the rules and me throwing the dice. He could have simply stated that Harmast, an NPC and another Sword of Humakt used in the campaign, had sent for me and I returned to him alone. Instead he killed me off and let the other players loot my corpse, including taking my much coveted Cornucopia which alternately provided food/drink when you spent a magic point on it (negating the need to buy and carry large amounts of food on long journeys. Which combined with Simon's geas never to drink alcohol wound up making him rather rich as he never wasted his money).
Like I said, it was a chickenshit move.