Is the 'Zira killing Sarabi' theory possible?

[ScarLoyal]

i've been seeing pictures of this theory quite a lot, and I wonder if it could be canon? Of course Zira and the outsiders weren't planned during TLK but it would explain her absence during SP (Other than Madge Sinclare's death.) And it would make Zira more scary if Scar's death made her murder Simba's mother, instead of just a defenseless lion cub.
And it explains the death penalty.

[TheLionPrince]

Fan fiction (or fan theories) can never be considered canon, unless the original creator(s) approve of the story/idea into the universe. The fan theory is possible, although this event is never mentioned during the movie. However, I don't think it's fair for Simba to lose another parent to a murder and for Sarabi to end her life on such a terrible note given the trauma they both experienced. I think it's best to think Sarabi died in peace sometime during the movie (or maybe after) knowing her son and his descendants are carrying on the legacy she and Mufasa once held.

Lastly, that "death penalty" ("If you need your pound of flesh, here...") was merely the punishment for trespassing into the Pride Lands, not the killing of a Pridelander.

[DGFone]

Also, Simba is fully aware that Kovu is Zira's son (adopted or not, I don't know). When he has the nightmare in SP of the stampede scene, he tries to save Mufasa, only to end up needing help himself and needing Kovu to save him, only to have Kovu turn on him.

If Zira had murdered Sarabi, I think that Simba's nightmare would have been much more related to that, because while Zira might be a fanatical worshiper of Scar, in the end, it was still Scar who killed Mufasa, and not Zira or even Kovu. But if she had killed Sarabi, wouldn't Simba be worried about taking in the son of the lioness who murdered his remaining parent rather than worrying over the legacy of Scar?

The fact that Scar remains the biggest roadblock to stopping Simba from accepting the Outsiders tells me that Zira did not murder Sarabi.