It will become impossible to ever use the serial port by other applications (like gpsapp) if you disable the possibility to change the baudrate and override config.ini options like car_rate= and notify=. Can't it figure the current playlist and song from data stored in the flash recovery area?

I'm already starting to worry that hijack is just trying a little too hard to do a little too much. Right now hijack would probably assume the player is restarting when gpsapp opens the serial port, etc.