If the 'love tap' rumour is likely to be true, a small female being punched in the face or side of head, by any male (even a pasty limp-wrist) would create potential for unexpected consequences. If the attacker delivered something more than a slap, they wouldn't have to be a big strong guy to do a lot of damage. The victim's brain can bounce inside their skull (along the lines of a knockout in boxing) and render them unconscious, doing damage or causing clots to the brain then, or other damage striking their head in the resulting fall. The artery in the neck can also rupture from any sudden forceful sideways jerking of the head. The initial blow or the unconscious fall could be just as bad as getting hit with an iron bar.
If something like this happened, the attacker could claim there was never any intention to kill the victim, simply delivering a single punch. There's been plenty of cases revolving around an unlikely single punch death of large solid males who were prepared for the blow, let alone a defenceless 60-ish kg woman (but fewer cases - or none I know of - dealing with the killer hiding the body of the victim).
But if a punch-too-far turns out to be the cause of death, and the killer isn't Gen Y and hasn't regularly used one of the media/platforms that campaign is targetting, their Barrister could pretty easily claim they never heard of the likelihood of a single punch being potentially fatal. I think it's a great campaign but not targetting the demographic of Allison's likely killer and nowhere near 'public knowledge'.
