> One legal thing that I'm also wondering about is the "Linux" trademark.
This probably explains why they never talk about Linux (at least I never saw it), but always about Ubuntu. I guess they have an agreement with Canonical.
It is perfectly legal to mention someone else's trademark. Else we would have text in books like "He walked over to the bar and ordered a popular sugared caffeinated beverage made by a company headquartered in Atlanta". You just can't say something that might confuse the reader into thinking that you own the trademark.
But doesn't calling it "Windows Subsystem for Linux" imply that actual Linux is involved, or even included? Suppose I marketed a range of flavoured additives to put in you Coke and called it "Simon's Flavours for Coca Cola"?
IANAL, but that would be perfectly fine ... you are totally allowed to write a piece of software, and say that it's for Windows, or for Mac. Or manufacture a piece of hardware that's for iOS, or Android. Or an aftermarket car part "for Honda", etc.
But Wine isn't 'for Windows' and this Microsoft thing isn't 'for Linux'. It doesn't involve the thing trademarked as Linux itself at all, in fact it replaces it. It's as though I wrote my own OS kernel with a Linux emulation layer to replace the Linux kernel and called it "Simon's Linux" or "Simon's OS for Linux". Suppose Wine renamed themselves "Linux Emulation for Windows".
The "for Linux" part is their hedge, I think. I recall Microsoft forced a project known as "Ultimate Windows Boot CD" to change its name to "Ultimate Boot CD for Windows".
This probably explains why they never talk about Linux (at least I never saw it), but always about Ubuntu. I guess they have an agreement with Canonical.