No, it didn’t. It ruled that the specific copying and use of that Google did with Java in Android was fair use, but did not rule anything as blanket as “you can copy an API as long as you re-implement it”.
1. Breyer's majority statement presupposes API's are copyrightable, without declaring it or offering any kind of test on whats acceptable.
There is no clear preexisting national case law on API copyrightability, and it is unclear how other, more general, case law would apply to APIs categorically (or even if it would apply a categorical copyrightable-or-not rule), so, no, its not “ok”, its indeterminant.
Edit: none of the large companies (except Oracle) are foolish enough to pursue a rule that declares APIs as falling under copyright because they all do it. In Google v. Oracle, Microsoft files briefs support both sides after seemingly changing their mind. In lower courts, they submitted an amicus brief supporting Oracle, then when it got to SCOTUS, they filed one supporting Google, stating how disastrous it would be to the entire industry.