There’s a difference between source available and open source. For example, actually being allowed to distribute modified versions is pretty damn important:
Restrictions
No Distribution of Modified Versions: You may not distribute modified versions of the software, whether in source or binary form.
No Forking: You may not create, maintain, or distribute a forked version of the software.
Official Distribution: Only the maintainers of the official repository are allowed to distribute the software and its modifications.
What is “actually open source”, if “here’s the source code” is not?
There’s a difference between source available and open source. For example, actually being allowed to distribute modified versions is pretty damn important: