1) Talking about infohazards, which aren't memetic. According to the 05 Command wiki (a separate, out-of-universe admin wiki for the SCP wiki) "An infohazard is an object that has an effect that triggers whenever you refer to it or describe it. This is separate from a memetic agent because it is still an object, not a piece of information."
2) Talking about antimemtics. Something can have an antimemtic effect without being a cognitohazard.
I removed two things from the page:
1) Talking about infohazards, which aren't memetic. According to the 05 Command wiki (a separate, out-of-universe admin wiki for the SCP wiki) "An infohazard is an object that has an effect that triggers whenever you refer to it or describe it. This is separate from a memetic agent because it is still an object, not a piece of information."
2) Talking about antimemtics. Something can have an antimemtic effect without being a cognitohazard.