Nainpur bypass line is not a blocker. Bypass line is needed when the handling station has too much load that it can't afford to hold the trains for 20 odd minutes. Nainpur doesn't qualify on that criteria
Prayagraj jn till date does a reversal for the trains which are coming from Satna and are going towards Varanasi, and Prayagraj's load is almost 150-200 times that of Nainpur. Gondia bypass is understandable as it comes on a trunk route...Chindwara, Nainpur bypass can help the goods, but it's not a blocker for passenger trains.