I wouldn't entirely agree - paths are representative of a file system hierarchy and "\\server" is a completely valid node in the UNC hierarchy, regardless of whether standard file system I/O function with that path.
In any event, it seems kind of like LabVIEW is going out-of-scope by deciding that because you can't enumerate that path, you should be given it to work with. It's somewhat similar to LabVIEW deciding to not return "dir" from "c:\dir" when you don't have permissions to "c:\dir". Moreover, LabVIEW will happily crunch out paths on for invalid drive letters all day long.
hooovahh was kind enough to walk by while I was typing this and mention, "Look! Someone on the Internet is wrong!" ...