One big question has been looming in the background of the series so far: How are Vivy's actions—which have time and again allowed AIs to prove that they are willing to selflessly give their lives to save human lives—supposed to stop the rapid evolution of AI? By all accounts, you'd expect the opposite to happen—which this episode shows.
Contrary to Matsumoto's originally stated objective and his insistence on keeping history as close to his original timeline as possible, their previous adventure has massively sped up AI evolution—bringing the robot apocalypse 20 years closer. Now humanity will be even more unprepared should the worst come to pass. Therefore, this time, Vivy and Matsumoto won't be saving human lives or protecting the reputation of AI—they'll be directly sabotaging their own kind.
The big point of contention this episode is Metal Float—a completely autonomous robot-run island factory which churns out parts for AIs and androids all over the world. But if you look at it in broader terms, it's also basically the first AI country. Vivy and Matsumoto's goal is not to destroy the island, but to simply shut it down until a time when humanity is better ready for something so advanced. A sudden, unexplained shutdown will not only show that AIs aren't ready for sovereignty but will also drastically effect the amount of AI parts out there, further slowing AI evolution.
The robot island itself is an interesting thought experiment. The AIs on the island know that coexisting with humanity is the only way for them to survive going forward. Therefore, they wish to be accommodating to humans and build a positive relationship with them. As such, even though they are more utilitarian in nature than their android counterparts, they are still designed to appear cute and non-threatening to humans. The problem is that there are no humans on the island and there never have been. Unlike Vivy who has evolved due to her interactions with humans, these robots are more like Vivy at the beginning of the series—trying to appeal to humans while not truly understanding what humans value.
Of course, Vivy's mission goes haywire when Toak moves to attack the island. Should the robots fight back and cause even a single human casualty, this could do much more than set back AI evolution—it could be the first step towards the complete extinction of AIs all together. Thus, Vivy and Matsumoto have no choice but to release the shutdown virus early so that when Toak arrives, all they'll have to fight against are unmoving, robotic shells. However, things do not go as planned as the robots instead go into full killing-machine mode in a scene that's more than a little reminiscent of the robot apocalypse scene that started off the series.
Now, why this happened is the big mystery. On one hand, it could be that the AI “Mother” detected the virus, stopped it, and decided to fight back with lethal force—which would be odd considering that Mother decided that building a positive relationship with humans was the best chance of survival for her island.
On the other, it could be that the virus was not what it appeared to be on the surface. If this is the case, it would mean that Vivy and Matsumoto have made a mistake in relying too much on the data from Matsumoto's original timeline. So much has changed at this point that perhaps people and their motivations have diverted from their original, historical trajectories—meaning Professor Saeki is far from the man who rejected the world's cultural values and married an AI.
Either way, we only have to wait until next week to find out.
• Vivy thinks that her actions with Matsumoto so far have increased her popularity—and therefore gotten her closer to achieving her goal. What she doesn't realize is that this is a coincidental byproduct of AI being considered so safe and selfless. Her current romp with Matsumoto is designed to lower the status of AI in the world—which likely will lead to a decline in the crowds she attracts and therefore making her mission more difficult. It'll be interesting to see her reaction when she realizes this.
• This episode has a cool bit where Vivy learns not only that the AIs have created their own culture but that she is a key part of it. This clearly shakes her to her core and she doesn't know how to deal with it.
• I love that the robot's welcome banner looks like its painted in blood—something that the AIs would never have realized without experiencing human interactions.
• I wonder if Professor Saeki was a member of Toak in the original timeline. Something tells me he wasn't.
• The marriage of Professor Saeki and Grace bugs me—not because she's AI and he's human but because her decision to do so isn't necessarily borne out of free will. According to the official website, her mission is “to save human life as a nursing AI.” So if she ever thought marrying him could help him live a longer life, she would likely do it. Love might not even play a part in it.
• If the creators of this show haven't played Nier: Automata, I'd be beyond shocked.