I'm not sure if this is helpful, but I thought it might be useful for you to hear a non-expert user's perspective.  (In summary, I'm agreeing with the OP.)

I spent a lot of time getting some signal handling working on OSX. Then finally in my process got to porting to Windows. I spent a bunch more time scratching my head trying to figure out why it wasn't working. Even after reading the os.kill and signal docs and searching for "Windows" I still wasn't clear what was wrong.  

This thread was the answer. 

So my suggestion at the least would be to put warnings in the signal doc, and clarify the language in the os.kill.