I don't know anything about Anubis. This thread is the first I've heard of it and as I said earlier I haven't even seen the website.
That said, I can certainly see a huge difference between something like AROS, which is API compatible and hopefully would continue to grow to be close to AOS3.9, 4.1, and MorphOS so that we can cross compile programs easily enough so they run on each system. I think Wookie Chat might be a good example of this.
Now, I could be mistaken about Anubis, but I could easy see something that really has nothing more to do with AmigaOS, than "looking like it", possible using such things as C, LIBS, DEVS, S, and concepts like Startup-Sequence, User-Startup, but on maybe a highly modified Linux kernal or something.
The internals wouldn't have anything to do with current Amiga Like OSes, but could to the user could be similar. Inspered so to speak.
:-)