No matter how you interpret 4.0 you are still allowed to explicitly license your work under CC 3.0. Other authors may very well feel differently.

The moral-ness of the JSON license [0] has caused some discussion [1] as to whether or not it actually is an open source license.

If your second example is true then that is the only of those three examples that would worry me (from a generic licensing standpoint).

[0] http://www.json.org/license.html

[1] https://www.google.com/search?hl=en&q=json+license+problem