I am out of my league here with Mike and Scott (heck I don't even know what the NUS is
but in my game I would have obstruction. Let me ask you this as a reason for my judgement. F2 fields the throw and then drops the ball as R1 slides into home and is stopped from contacting the plate by F2 reaching for the ball. I think that is clearly OBS. To me I don't see the difference between losing the ball because of fielding error or because of a LEGAL slide at the base.
Back to the question at hand. Fielder had control of ball, blocked plate, OK no OBS. Fielder lost control and was still blocking runners progress toward the plate (this is the HTBT part) if this is true then I see OBS, runner awarded home. I think we had a long thread about this last year when this rule was changed. It is like there can no longer be a train wreck, no control of ball and blocking runner it is OBS, runner intentionally doing something to cause a fielder to miss a ball (or field a batter ball etc.) then you have interference.
Again these are JMO.