The answer lies in the very same statute -- referenced in the New Hampshire delegate allocation primer from December -- that determines the proportional allocation of delegates in the Granite state, Chapter 659, section 93 of Title LXIII (Elections). Part VI of that code establishes the following:
If a presidential candidate has received a share of the delegates as a result of the presidential primary but withdraws as a presidential candidate at any time prior to the convention, his pledged delegates shall be released by the candidate and each delegate is free to support any candidate of his political party who may be his choice as a candidate for president.
Now, John Huntsman
withdrew from the race suspended his campaign on Monday (January 16) and immediately endorsed Mitt Romney. However, that endorsement does not automatically shift the two delegates Huntsman won to Romney. Free of the bond of the candidate to whom they were pledged, those two delegates are free to support any candidate they choose -- independent of each other -- in between now and the convention in Tampa. In other words, the delegate pledge is not transferable when and if a withdrawing candidate endorses a still-competing candidate. The reality is that those delegates are very likely to be Romney supporters in the end. But there is no formal route for that endgame. Those two delegates may remain unpledged heading into the convention and support the presumptive nominee there, or they could stick with Huntsman or move now to any other candidate and hold that preference up to and through the roll call vote at the convention. The former is most likely, but a move to Romney -- in the interest of unity -- now would not be at all surprising either.
NOTE: For now those two delegates will remain in Huntsman's column until the point at which there are reports that those delegates have pledged to support another candidate.