And you as the operator of the bot would just end up in a war with people who have different ways of expressing the same thing without using those words. You'd be spending all your time doing that, and lest we forget, there are a lot more people who want to disrupt these bots than there are people operating them. So you'd lose that fight. You couldn't win without writing a preprocessor so strict that the bot would be trivially detectable anyway! In fact, even a very loose preprocessor is trivially detectable if you know its trigger words.

The thing is, they know this. Having a few bots get busted like this isn't that big a deal, any more than having a few propaganda posters torn off of walls. You have more posters, and more bots. The goal wasn't to cover every single wall, just to poison the discourse.