I think there are two separate claims being made here.
Don't be sure that your self created metaethical system works
Be confident in using commonly used metaethical systems
I can get not being overly committed that your own metaethical system is the ultimate truth. But it does not follow that established and commonly used systems are any good either. Considering that for a large number of people, their source of ethics is whatever they were indoctrinated to believe in as children, I would not place a lot of confidence in existing metaethics even if I am not confident in my own.
Edit: The main suggestion of this piece is #1 but the using existing crypto methods seems to suggest #2. The debate then becomes about what should one do when inaction/further research is not an option, when you have to make a decision.
I think there are two separate claims being made here.
I can get not being overly committed that your own metaethical system is the ultimate truth. But it does not follow that established and commonly used systems are any good either. Considering that for a large number of people, their source of ethics is whatever they were indoctrinated to believe in as children, I would not place a lot of confidence in existing metaethics even if I am not confident in my own.
Edit: The main suggestion of this piece is #1 but the using existing crypto methods seems to suggest #2. The debate then becomes about what should one do when inaction/further research is not an option, when you have to make a decision.