There are many OS kernels out there that use the ELF format for executable binaries. Many of them are not one particular Linux kernel. The fact that there is a series of articles based on the changing Linux kernel no longer accepting the old "tiny ELF" files is important.
I'll give kudos to the authors of these articles because they're doing something clever and fun. I just feel the urge to clarify to the internet that they're poking at exploits in a Linux kernel loader by offering it non-standard binary files and not creating tiny ELF files at all.