Exchanges can list anything they want. Even ETH placeholder for coin that is not even in Testnet stage. Qtrade listed Idena in February when it was clearly a testnet with less than 200 nodes. But i agree that it is no longer testnet. I only don't know why Andrew is quiet about it:
"The seamless hard fork update mechanism is a major step towards decentralized onchain governance. We consider the Idena blockchain to be switched to the mainnet status once the network becomes capable of seamlessly upgrading protocol versions based on the agreement of the network’s majority. Every validated participant will be empowered to decide which node version to support."
https://medium.com/idena/idena-hard-fork-announcement-d194f8816d3704.11 we had first seamless upgrade so network is capable of seamlessly upgrading protocol versions so its mainnet
True, maybe they are quiet about it as a precaution measure. If anything goes wrong. Remember the glitch from epoch #46, where half the network were killed/suspended?!