"Villain" is subjective. Antagonist, certainly.
It doesn't matter why. What it solves is that it is the AI - that the thing they're using to isolate themselves from the rest of the world is what's killing them.
"We need to maintain stronger walls to keep the Bad Things out" is definitely not the message they were going for.
Murdering people for fun is villainous even if they're bad people, especially if you're doing it by having monsters eat them. The AI committed genocide since it murdered EVERYONE. "Does a society deserve to be saved" isn't the same question as "Should you murder everyone in a society that doesn't deserve to be saved?"
And it does matter why because that's the entire point of the episode and we don't even get an answer beyond The Doctor guessing despite knowing very little about the situation. Which goes back to my complaint about this season relying way too much on telling over showing.
And my point about the wall was about social media causing people to neglect (or actively tear down) the things that keep society safe and functioning. "Get vaccinated or you'll get sick and endanger others," "Vote or fascists could get into office," etc. are important messages that social media is actively trying to deny and drown out for crying out loud.
yes but we're nerds so there must be a meaning to everything.
Every other Doctor Who threat gets some kind of explanation. The Doctor even acknowledged the times he can't like in The Giggle when he was explaining he couldn't explain The Toymaker's powers.
In fact one of the plots in this season is the supernatural leaking in and how it doesn't play by the rules of our universe.
"The AI got slugs it can control from somewhere" isn't a satisfactory answer when Doctor Who has been so good at this before. Fans deserve more than the equivalent of "Somehow Palpatine returned."
Space Babies was better about explaining things than this episode and it was entirely exposition!
but "Boring, we cant be bothered" was
Exactly. It's what we're seeing in real life where people are complaining on social media about doing the boring/hard but necessary things to keep society functioning and safe.
If they want an actual satire have people deny the slugs even as they're watching them eat people, have them keep insisting that all you need to do is sprinkle salt on yourself to keep them away even as they see that salt does nothing, claim the slugs are only eating bad people, purposefully try to get people eaten by them, have people compete in "The Get As Close To A Slug As Possible Without Being Eaten Challenge," etc.
ACTUAL problems with social media as opposed to an AI villain who didn't even need to exist for this episode to work.
It's like this:
I will say that I'm glad they finally gave The Doctor stuff to say that wasn't exposition or anecdotes and I loved it.