The wording in question:

5. The copyright holder reserves the right to revoke this license on anyone who uses this copyrighted work at any time for any reason.

And his explanation from the README:

Lamson is licensed under the license in the https://github.com/zedshaw/lamson/blob/master/LICENSE file. It's a variant of the BSD license that is revokeable and makes contributor's rights clear up front.

It's a phenomenal idea. I'm gonna start buying stuff in revokeable cash.