You might be surprised at what the state of the art is in very limited fields like this. They wouldn't be able to engage in back-and-forth, but seeing a tweet that says "@amazon just pay your workers more", a bot can churn out a response of "Did you know that Amazon pays warehouse workers 30% more than other retailers?" pretty easily. One human just writes 1,000 responses and maps them to various keywords. Scan for those keywords and pick a response that fits the keywords best and boom, done. Completely automated.