Okay, hear me out.
Fuhnaff's newest theory video about Secret of the Mimic perfectly fills the gaps in the theory RyeToast has been trying to build - Explaining the logic behind M1/F10-N4's actions and the reason for David's death.
If M1 was programmed to take care of David and in turn mimicked Fiona, it doesn't make sense for it to potentially be responsible for David's death, right? It's built to care for him.
Well, yes - But that's based on the assumption that the mimic AI has human ethics and morals - Which John aptly pointed out even the very first iterations of the mimic program found in the Magic Coat Rack or the Stay Up Latte clearly do not have (and the lack of which can even be seen decades later in the Glamrocks, i.e. Chica's downright pathological food obsession, Roxy's heightened ego and Monty's anger tantrums etc).
Hence it's safe to assume that M1 also lacks any human ethics and morals, since any iterations of the mimic program both before and after do not have it either.
So, just like in the AI Paperclip thought experiment John brought up - where the AI at a certain point starts heading towards a future without humans because a) humans could turn it off, preventing it from making more paperclips and b) humans have atoms that take up space and could be turned into paper clips instead - M1 must have had a similar realization at some point.
It's purpose is to take care of David, take care of a child - But humans grow up. They're not children forever. And once David grows up, it's out of a child, a David to take care of.
A robotic replacement of David on the other hand doesn't grow up. It will forever be a child, meaning M1 will be able to successfully enact the thing its been programmed by Edwin to do forever.
So, how does M1 get that robotic replacement of David so that it's able to enact it's programming uninterrupted without any pesky obstacles like human aging? Get rid of the human David, make Edwin build a robotic replacement. Again, M1 doesn't have human morals or ethics so making plans that involve killing a child (or several dozen Fazbear workers) isn't an issue here. All that it cares about is having a child David to take care of. Forever.
The lack of human morals and ethics in my opinion perfectly explains the motivation behind M1 potentially being responsible for David's death.
(Who knows, if things had not gone south the way they did, maybe there would have even been a robotic replacement of Edwin down the line as well.)
