Seriously. The author seems to have no idea what the Windows Subsystem for Linux is nor how it works. There are separate file systems for a reason. The things the author tries are exactly the things Microsoft make it very clear will be very problematic at best.
The POSIX model and the Windows model of permissions are completely different. Instead of trying to map between the two (something Cygwin does variably well, sometimes really badly), they provide a file system with the semantics needed. Finally, there is no Microsoft version of Bash. It's Bash, compiled for the Linux kernel (like most packages) that is being run as is by the subsystem. The subsystem has bugs, this is known, this is beta software and it is software that even Microsoft is smart enough to know that they need as many people trying it to find bugs as needed.
And it does fill a very specific need and more importantly, it's further building out the newer subsystem parts of NT, which might come in handy for other things down the road.