Ahhhh, you're reference to the planted evidence was actually Mackay himself claiming the pom-pom was planted. But he was the only one suggesting that (along with a few conspiracy bloggers at the time).
More importantly, your speculation link does seem to require that one accept that the Saanich PD are complicit in railroading Mackay, a leap I don't personally choose to make.
I guess underlying all of this, and worth remembering, is that Mackay himself had admitted to assorted parole boards multiple times that he "was capable of killing her" ... but that he doesn't remember doing so due to the fact that he (claims) he suffered from lengthy black-outs at the time, during which he felt he would have been capable of murder ... but also during which he has no memory.
The record is also solidly established that he made reference to killing her multiple times to other prisoners ... prisoners who then reported those conversations to the authorities.
Being a prison house confession though, it is as dubious as all prison house confessions might be.
Regardless of doubts or conspiracies, the evidence was certainly enough to convict him to prison for life ... and he's all but admitted that he killed her.
All that's left is for him to do is to divulge the location of Marguerite.