After having a closer look I fear that there isn't a correct implementation for half closed sockets and returning True from eof_received results in a fundamentally broken state machine.

I'm not sure if a selector implementation can handle half closed sockets, at least I'm pretty sure that this is not supported on Windows (https://docs.microsoft.com/en-us/windows/desktop/api/winsock2/nf-winsock2-select).