It is a PostgreSQL Blockchain Extension, i.e.: a postgres extension [1] which allows one to process a blockchain [2].
The bitcoin blockchain is the first invented blockchain as we know it, all the other blockchains are borrowing the concepts from the bitcoin blockchain, which is why this extension, at least in its present initial form, is designed to work with the bitcoin blockchain.
[2] "The first distributed blockchain was conceptualised by an anonymous person or group known as Satoshi Nakamoto" from https://en.wikipedia.org/wiki/Blockchain
Just because an Oldsmobile is one of the first mass produced automobiles in existence, doesn't mean anyone looking for a car would want an Oldsmobile.
In regards to database technology, Bitcoin just pieced together technologies that already existed, i.e. hash cash, merkle trees, and distributed databases.
It's worth acknowledging while Bitcoin was a great prototype for implementation of a blockchain, it's quiet stagnate and divided community and development teams has led to the current crisis of hard forks. Meanwhile other blockchain projects are iterating and developing user-friendly features.
The bitcoin blockchain is the first invented blockchain as we know it, all the other blockchains are borrowing the concepts from the bitcoin blockchain, which is why this extension, at least in its present initial form, is designed to work with the bitcoin blockchain.
I stand by the name, it is exactly correct.
[1] https://www.postgresql.org/docs/current/static/external-exte...
[2] "The first distributed blockchain was conceptualised by an anonymous person or group known as Satoshi Nakamoto" from https://en.wikipedia.org/wiki/Blockchain