Operators are what assemble the bindings in the trie. Anyone can become an operator by bidding in an auction. You can read more about it at https://spacesprotocol.org
they don't have much power besides adding your name -> pubkey binding in the tree.
Who can update and publish the merkle trie onto the blockchain? Is it only Spaces themselves who can? If so, this seems a little inferior to more direct blockchain solutions like the Ethereum Name Service which exists as a smart contract on a blockchain that anyone can use directly.