No, but the clause in that license is gross. He can sue any of his users at any time if he decides he doesn't want them to be his users anymore. It's by Zed Shaw author of Learn Python the Hard Way, I'm surprised by this. In any case it looks like Lamson has not been updated since 2013.
The clause:
The copyright holder reserves the right to revoke this license on anyone who uses this copyrighted work at any time for any reason.
The clause:
The copyright holder reserves the right to revoke this license on anyone who uses this copyrighted work at any time for any reason.