It’s not a blockchain. It’s meant to be a ledger database so it works in a similar way to a Blockchain, same internal data structure, but without the distributed consensus concept.
So it is a blockchain, just not a distributed blockchain.
The idea of a blockchain for tamper detection, with external validation by regularly sending off a current state hash for signing, existed long before crypto currencies arrived with the distributed verification process.
It is by the original definition. Though not by some of the recent redefinitions but as they are often due to marketing getting good of the dictionary...
