You asked about RS232 ;-)

Usually, the flow control on the RS232 link between DTE (eg, your 8051) and DCE (eg, your bluetooth module) affects only that link; it does not travel "over the air"

eg, when you connect a PC to a modem or ISDN TA, the flow control setting only affects the RS232 link between the PC and your modem/TA; the protocol between your modem/TA and the remote modem/TA would have its own "flow control" mechanisms.

I wouldn't be surprised to find that your bluetooth module works in a similar way.