But see this isn't the first time the show has used Love[TM] in lieu of a scientific explanation--last season it was stated that the outcome of which universe survived hinged on which Olivia Peter chose

then there was episode "6B" that talked about Love[TM].
Fringe always uses some crackpot science in their stories but the whole love angle for the series' mythology is lame--it reminds me of the whole "only love can produce a Cylon child" from nBSG.
It just is bullshit of the worst kind. People love family members and despite that people still die or can't be cured of serious illnesses. Alzheimers patients have loved ones but they still isn't enough to protect those memories.
In my opinion the only thing the show had going for it was its mythology and over the last two seasons they managed to fuck it up--it smacks of the same weak writing of LOST or nBSG where the writers can't come up with anything clever after building up these arcs for years and in the end go for the lazy and cheap magical mumbo jumbo route.
Fox just needs to put this show out of its misery and try to find something more worthy to fill its slot next season. The writers have had four years and they've drug their feet with boring filler and a drawn out arc.