They can't keep up with the flood of posts can they. They don't have enough manpower to do it all. They are probably in the area of a billion tweets per day. There is no way they can possibly find it all.
Kek, not only a test, but also a trap
AI is expensive and slow. Faster than people, but still slow. We can out flood it with enough variation. This means we can also be flooding redpill memes alongside our fisa memes because those will need to be checked too.