Is license-free a good idea?

The liblfds project [1] (disussed in [2]) has the following license:

    license

    There is no license. You are free to use this library
    in any way. Go forth and create wealth!

    If however for legal reasons a licence is required, the 
    license of your choice will be granted, and license is 
    hereby granted up front for a range of popular licenses:
    the MIT license, the BSD license, the Apache license, 
    the GPL and LPGL (all versions thereof) and the Creative 
    Commons licenses (all of them). Additionally, everything 
    is also placed in the public domain.

Not to pollute the other discussion I decided to ask the question here:

Is this a good idea?

Food for thought:

* Some of these licenses are not compatible. Probably no problem because only one license applies at a time?

* As far as I can tell all mentioned licenses (even CC0) have a disclaimer. Does the disclaimer apply? Does the public domain part leave me in danger of a lawsuit in a jurisdiction where the disclaimer is necessary?

* Public domain doesn't exist everywhere (though this is controversial [3]). This no problem if you place your work int the public domain and offer other licenses in places where no public domain exists, like SQLite does. But what if you offer free choice?

[1] http://liblfds.org/

[2] https://news.ycombinator.com/item?id=11805728

[3] http://cr.yp.to/publicdomain.html