I understand how git works. I'm discussing the edge case scenario where someone uploads something but doesn't add a license. In that case, forking and cloning should be disabled, at the least.
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.
The point of uploading to a public Github repo is to let others clone it. Pure tech tools like that shouldn't implement features that require searching a repo for a file that could be a license and then determining whether the file gives others the right to do that clone. After all, letting others clone is the entire point of the tool. If it's not allowed, don't use the tool.
This seems a reasonable balance.
I'm specifically discussing a situation wherein someone has uploaded non-licensed code to github. I am not advocating for this. I am discussing what should be the default behavior for a repo if unlicensed. Another alternative is not having the repo be usable at all (so not private) if one attempts to bring it public without a license.
And you are continuing to misunderstand how this works. If you can view it, you can copy it. Nothing prevents someone from viewing a public repo. So nothing prevents someone from copying it. Therefore any attempt to make it difficult is just a PITA.
That's why Github has a default license for all non-licensed public repos. Because it's a public repo. If it wasn't supposed to be available to copy, the source code shouldn't have been made a public repository.
So again. If what you're looking for is a private repo solution, Gitlab offers this enterprise-level solution for free. You are barking up the wrong tree.