Using the NWC peg as a buyer

QoE came back on a deal I have under LOI as L12M $210k and L3M $350k (increase in AR).

I expect this NWC peg should come off the top of the purchase price, but the seller thinks it's prorated based on months to the end of the year.

With no hypothetical risks on this deal, should I dig in with the seller? I assume so. Looking for experience to guide me.