I don't see how releasing the mainnet client would mix with the exchange selling IOU tokens. The mainnet would not interface with yobit or anyone else selling IOU's. There is no real network connected to the yobit waves market it is just a fictional wallet they opened with X amount of tokens. Depositing and withdrawing from them wont work. There is no deposit or withdraw options for the people buying wave tokens on yobit.
THIS, people need to learn to read, Sasha SAID: Yobit will not be getting full node source code.
I think this should not be the case . Yobit is an exchange with appropriate license . Eventhough making IOUs from ICOs is financially unethical, it is very hard to stop this practice. Better for future ICO to have a contract of sorts between exchanges before launching a project.