I'm pretty sure you cannot read an existing file that would cause the recursion bug regardless if the OS's file name case sensitivity. This bug was fixed a long time ago. The warning should be on the case sensitive file systems to prevent the user from creating or reading a schematic that could not be loaded on case insensitive platforms due to the recursion check failing on schematic load.
I'm pretty sure you cannot read an existing file that would cause the recursion bug regardless if the OS's file name case sensitivity. This bug was fixed a long time ago. The warning should be on the case sensitive file systems to prevent the user from creating or reading a schematic that could not be loaded on case insensitive platforms due to the recursion check failing on schematic load.