(Edited: mixed it up on the last sentence.)
Which is exactly what the post says this is. It's running Windows 9x on Linux kernel. It's strangely worded, but from the follow up comment, and the readme in the repo it seems clear that it's running on the Linux kernel.
Pretty sure it's the other way around. But I haven't had my coffee yet ;)
Microsoft's naming scheme confuses me every single time though: "Windows Subsystem for Linux" actually runs Linux on Windows...
I missed the part that it runs on the bloody Windows 9x kernel, I was to busy thinking about modern Windows.