While your overall proposal has some attractive elements, we ought to keep the issue of fairness at the forefront of the discussion. In this context, fairness means treating all US-NBT holders the same. If we give more to a select holder of US-NBT, all other holders will receive less. That wouldn't be fair.
The way to make it fair is to give all US-NBT holders equal access. One way to do this would be to place the BTC on Poloniex. In theory, B&C NuBits could be sold to receive the BTC on Poloniex. In practice, it is possible that other US-NBT holders would consume the BTC liquidity, as fairness requires. There is also the issue that B&C will not have possession of any US-NBT in a few days. This motion mandates the transfer of B&C Exchange NuBits to me at this time, with the understanding that the funds will be in escrow until they are exchanged for NSR, which will occur when NuShare holders pass a custodial grant. However, a form of @Dhume's proposal could work if and when B&C acquires additional US NuBits.
It worth pointing out that this is a proposal that appears to have considerable FLOT and community support and might also use the BTC for the shareholder mandated purpose: purchasing NuBits. So, I am keen to see a form of this proposal move forward that would bring the value in these BTC under shareholder control. However, I am struggling to discover a way this could be done that is both fair to all US-NBT holders and complies with the shareholders directives in this motion.