It's deja vu allover again!
At the time R! was obstructed where did BU believe R1 was going to end up sans the OBS? Not including playing action after the obstruction. The ball was in the infield at the time so I admit I have a hard time seeing protection beyond 3B.
Remember, we don't "add on" to the end of the play. The decision as to whether R1 should be protected to 3B or home should already be made before the bang-bang play at the plate happens.