The Lil license seems to have a patent grant [1]:

> Permission is hereby granted by the authors of this software, ... and including usage rights to any patents the authors may hold on it, ...

And CC0 does not [2]:

> No trademark or patent rights held by Affirmer are waived, abandoned, surrendered, licensed or otherwise affected by this document.

That appears to be the motivation of this over other existing, minimal licenses.

[1]: http://lillicense.org/v1.html

[2]: https://opensource.stackexchange.com/questions/133/how-could...

Creative Commons advise users against using CC0 for code. CC0 also got caught in a technicality, causing it to never get approved or disapproved as an open source license by the OSI.