[r3bl]

There's nothing stopping you from entering anything in the LICENSE file, including an open source license, a copyright notice, or something completely unrelated to the license of the project.

With that in mind, to enforce your argument, they would need to create a list of licenses that are okay to fork/clone. Why should they create a finite list of that?

I'm willingly using WTFPL[0] that can be summarized as "as long as you change the name, do whatever the fuck you want to". I know it's not a serious license (I only use it for non-important collaborative Markdown documents I've started), but thanks to its use of the word "fuck", I'm having hard time believing that it would find its way into any whitelist. FSF mentions it on their website, but GitHub doesn't list it as an option on choosealicense.com.

[0] http://www.wtfpl.net/