Well, the basic reason is that TiMidity doesn't work in real time.
Only when the song has been completely read will it start to play. However,
you can save the song to a midi file and then play it with TiMidity,
and this does sound great (if you've got the right patches)
The source for the SB16CTRL program that is used to modify
the runtime behaviour of the SB16 emulator is included in the patch. There
is also a few binaries available. The OS refers to the one running under
Bochs, not the one running Bochs: