He is not the first to claim to be Satoshi Nakamoto, only the most brazen. And he will not be the last. Mark my words! There is a big incentive for criminal imposters to pretend to be Satoshi Nakamoto.
the silver lining: satoshi's pseudonymity may have enabled imposters, but it also allowed him/her/them to disappear completely unknown. that was a massive win for bitcoin's decentralization.
in contrast, it would be virtually impossible to impersonate vitalik buterin. the trade-off for ethereum is they forever have a "benevolent dictator". that trade-off isn't worth it IMO.