I know Howard collected plenty of flack and threat's particularly over gun laws and the unions were certainly sticking it to him over work-non choices but don't recall public figures (union official's or gun association officials)suggesting he should be killed and dumped in a chaff bag or the like but happy to be proven wrong.
No you are correct (and I'm to lazy to trawl). Howard was wearing a bullet proof vest at one stage (1996?) and had to have extra security around his home. Howard and Peter Reith copped a lot of death threats during the 97-98 waterfront dispute. But can't put a finger on public figures that joked about wanting him topped.