Charge him full cash price for his medical care. Since he probably doesn't have it, deduct the cash amount from the money we undoubtedly give Liberia in Aid. (We spent in on aiding their citizen after all). Fly him to the Liberian Embassy, and drop him off with the bill and explanation.
That way the hospital gets paid, it's a zero sum game for the US taxpayers, and Liberia can decide if this kind of subcontracting is worth the cash cost.