jocrmn Making a client for BO3 is a surefire way to get the entire Plutonium project shut down by Activision. I highly doubt anyone wants to see that.
The argument of "Buy the game" is absolutely valid for BO3 because the game is still in a playable state with almost full functionality that a custom client would bring. (Custom maps, dedicated servers, mod support, etc.)
Since all of those already exist in BO3 Steam, there's genuinely no reason for Plutonium BO3 to exist.
If you cannot afford the $60 to purchase the game, you can look at other third-party websites that sell games for cheaper (G2A for example) to try to find the game for under $60.
If you cannot afford from a third-party site, then maybe you should just be playing other games that aren't as expensive.
Games are a privilege, not a right.