How do they "get burned" by that? Not having a license means you don't get to use it and are violating their copyright if you do so (possibly except the things specified in Github ToS: look at the code on github)
The default is that you don't have rights to code unless they are explicitly given to you. The Github ToS do specify some rights that are granted through uploading to GH, but they don't constitute any usual license, nor one that makes any of it usable to you.
No. If you find some code online, or on a thumb drive on the sidewalk, and it is unlicensed, it's incorrect to assume that it's equivalent to being permissively licensed for you to do whatever you want with it.
Yeah, I edited my comment as I think I miss-spoke actually. Technically, GitHub as a platform will allow us to fork or clone this code. But with no license file, from a legal point of view, we cannot use it, or whatever else an open source license would allow.
I don't think you have much responsibility in not specifying a license, since it defaults to "all rights reserved", thus preventing anyone else from using that code.
Surely the author is bearing the liability of getting burned by not specifying a licence.