"In order for an invention to be patentable it must be new as defined in the patent law, which provides that an invention cannot be patented if: the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention” or . . ."[1]
[1] https://www.uspto.gov/patents-getting-started/general-inform...
...oh, before the effective filing date. There's the rub.
But couldn't the case could be made that all of those conditions applied at the time Satoshi released it; and, had the rightful owner known of its existence, would have applied?
I just think the anonymity is really interesting. Why be anonymous? I don't think it's open-source altruism like the mythology suggests. I think it's greed. If he'd developed it for someone else or while working for someone else or on/with (their) prior art, that's a damn good reason to hide. So is (at present) the $6.4 billion USD value of his 980,000 bitcoins.