This is just an educated guess. But if NMM's ships are locked into rates for the next two years and the BDI is recovering then they need to be able to tap into the higher rates to compete with the other spot shippers. New boats - big blue shiny ones I hope - will be able to charter at the more advantageous rates and thus add to the bottom line. As long as the offering isn't being used to pay down debt - think DRYS - this should be an alright thing.
You did a lot of work with the numbers for potential future cash flows but why take the risk. I agree with the other commentator who questions why anyone would pay $125M for something you can buy for $60M or so.
NMM has done nicely since the yoke of TBN1 was removed. Why climb back into a hole.