@codinghorror how do you feel about this?
I worry that adding a fourth “Edit Wiki” permission is a minefield. There is a lot to explain to site moderators about this new toggle.
Adding a security fundamental building block is not a light change, we would be talking probably week or 2 to get this all right, there are tons of touch points.
Does simply amending it so you must have “create” permission to edit a wiki in the OP solve your problem?
This may be workable as a change and does not introduce new primitives.