Given they're active on the list in question and while the content crossed a line, the style was not out of character, nor was it later claimed to have been posted by somebody else, so I think we can rule this out.
Why not publish the offending emails? As it is, those who threatened you face no repercussions. Their tactic worked, and they have every incentive to visit abuse upon others in the future.
Edit: Thank you. I was under the impression that the emails were addressed specifically to you, not a mailing list.
They're on debian-devel, and I'm sure the hivemind fill find them quickly enough, but sure: https://lists.debian.org/debian-devel/2014/05/msg00585.html (and yes, they got pushback, but it took approximately that much until people said WTF).
Thorsten has always been a jerk. I don't think systemd is a new trigger, but it's interesting to see him show up (though I'm not surprised). He used to haunt the OpenBSD lists a decade ago, but was basically sent packing after all his "contributions" were rejected.
Edit: Thank you. I was under the impression that the emails were addressed specifically to you, not a mailing list.