3B8CF, Jacky, Secretary of the Mauritius Amateur Radio Society, says the local telecom authority, ICTA, has told him no license (including 3B9DX) has been issued for Rodrigues recently for anyone.
A recently reported operation was apparently, thus, illegal and probably "a joke by somebody who wanted to have some fun," says Jacky.
The apparent pirate was QRV for a couple days in late April/early May on 20 and 15 CW.