Accused of Murder section 302 & bail

Dear Respected Sir, A friend of mine has been charged with murder under section 302 after he got into a scuffle on the road. The deceased was on his mobile phone while driving & when corrected by our friend, he used derogatory words. This provoked my friend and that's when the scuffle followed. My friend held the deceased by his collar and after a crowd gathered & intervened, my friend left. The deceased walked towards his car too but fell unconscious and was taken to the hospital where he was declared dead.The postmortem report clearly indicates the deceased died a natural death-a heart attack with no external injuries anywhere on him. My friend's bail application on the basis of the postmortem report was denied by the lower courts as the prosecutors want the awaited CFSL report. I want to know that first of all can the section 302 charges be justified? At what stage can my friend reapply for bail and what are the chances of getting bailed out in the lower courts? What should be the immediate steps to ensure his acquittal or get him bail?