A lot of coders who have had to implement APIs will disagree with the thrust of this artiicle
You have to be able to do your own implementations of public APIs - that's what APIs are for
Longer ago than I care to remember I wrote an ODBC driver for a database (not naming it here as it was commercial work not FOSS) to fit with MS ODBC API as some customers wanted Windows ODBC access to the db to use some third party tools (coded against ODBC 2.0 should give an idea how long ago)
So I implemented the ODBC API for teh database we sold, writing the code behind each API call (non trivial) - that's the whole point of an API - a "standard interface" that companies can wrap around their software / hardware (as appropriate) to allow inter interoperability & there were zero copyright issues involved.
So long as Google did their own API implementations (and did not just copy & paste Oracle code that *implemented* the API) then should be no issues