It's fine to create bots if the social media platform allows it. Just make it clear that they're bots if that's the platform's policy.

If you disagree with Twitter's policy here, then that's a separate question, but here's my (I think, uncontroversial) opinion on that: Banning the automatic creation and puppeteering of masses of fake people seems like a pretty good policy along a number of dimensions - especially just for keeping authentic users from leaving your platform.