There are no `kill` function in Windows API.
From my perspective win32_kill was added to emulate posix sibling if possible. If not — better to give another Windows native name to that function.
Really don't see good solution. Maybe better what we can do — declare what os.kill cannot be called with 0 signum on Windows for proc presence checking and note that fact in os.rst.
Terminating process looks like overcomplication. POSIX kill only sends signal to process and nothing more.