But what problem do you really want an answer to? If you want to know that you will create a new file (if possible) by writing the file name, this seems to be the normal behaviour.
Actually, Stdio.File(..., "wcx") doesn't work on a dangling symlink. Another case is rm() which shouldn't fail with System.ENOENT if and only if it exists. Yet another is mv() which can move a dangling symlink perfectly fine.
So the query makes sense in many situations. But above all I want the most natural behavior given the function name, and instinctively I think even a dangling symlink really do exist - it affects its surroundings by showing up in directory listings, it got a pointer, owner and group that can be queried, etc.