Linux is among the worst Unix implementations ever, not giving support to true Unixes like Sun Solaris, IBM AIX, *BSD, OS X and so on will make their effort a failure. If they were going Unix only it would have made sense.. but what's up with the "Linux only" thing other than some pathetic marketing hype attempt ?

The subjective view that linux is among the worst unix implementation is not in the least bit relevant given that Linux is the most popular (and least antique) unix implementation. For the record, I've used most of the unix implementations and of them all, I prefer Linux. YMMV (not that I care).

Really, if it works under Linux don't tell me it won't work under a true Unix.

What matters is that it won't work under Windows.

Read carefully. It specifies that they'll be implementing it into the linux kernel. Owners of other OSes will undoubtedly be quite capable of making the necessary additions on their own or with help from Oracle, they'll just lag behind a bit initially.

Windows, on the other hand... Well... You might get lucky and have support in 10 years or so, that is, kernel support that actaully works the way it's advertised.