I'm not sure I understand the summary of the "exploit" -- it sounds as if it can affect the ELF filesystem, but it still requires Windows' Kernel32.dll in order to do so. This doesn't make it cross-platform, it just allows for affecting non-native file systems.
So, either I'm missing something, the write-up is wrong/incomplete/misleading, or this isn't really a "cross-platform virus".
I'm thinking that the write-up is probably just poor writing. Perhaps the author doesn't really understand exactly how this proof of concept works.