I deployed Windows 3.1 in production.

It was horribly unstable and crashed if you gave it a nasty look. Running BSD binaries on top would give the unpleasant combination of an unstable GUI with weak multitasking, on a primitive OS, plus hard-to-use unfriendly binaries.

Not a winning combination.

To me, it sounds like MachTen on Classic MacOS.

https://en.wikipedia.org/wiki/MachTen

BSD in a window on an OS with no good multitasking, virtual memory, or networking.

So, it lets you do stuff the host OS couldn't otherwise do, but it doesn't mean it does it well -- because it doesn't.