Obstructed runner retreating after reaching awarded base

[NCASAUmp]

Take the following sitch:

ASA. No runners on, no outs.

B1 hits the ball safely to left field, where the LF bobbles the ball on the ground. As the BR approaches 1B, F3 is standing on 1B. The BR significantly widens their turn, missing 1B entirely. The BR advances all the way to 2B and stops, then retreats to 1B to tag the missed base. Upon tagging 1B, the runner decides to go for 2B, where he is subsequently tagged out.

In the BU's judgment, the BR would have reached 2B had there been no obstruction. When the runner got tagged out at 2B, was he protected? Or, upon reaching their awarded base, was the protection removed?