This package is really old and the last commit is 8 years old. Also it probably needs updates for newer Android versions past 4.4. Is there any good reason why it still should be added to nixpkgs?

I used it yesterday in an attempt to fix my phone, so I figured I'd PR it.

It is still pretty old and probably needs patches in the future to work when packages it relies on get updated.

It is pretty old, true.
It only depends on zlib and that seems to be a pretty a stable library, no?

On the other hand, this looks like a pretty niche package, and it has hardly any documentation, so that might be a reason not to ad it.

I only PR'd it cause I had built it since I needed it, so it was easy enough for me to offer it to the community and let you all decide if it should be in nixpkgs.

As an alternative for such outdated packages, consider contributing to NUR.

Indeed, since upstream is unmaintained, the NUR seems to be the most appropriate place.