"this Diwali" You yourself did elucidate your comment. The "AC Special" got patronage only because of seasonal festive rush. AFAIK Humsafar won't be a seasonal special and would rather be a regular train. Moreover, if the special would have remained so clogged with passengers, the runs would have got extended, most probably, for a month.
"please see the atlas of BIHAR" I see not much difference in the railway density of both the states. Astonishingly both MP and Jharkhand to the south of these states depict way low densities.