[DeputyUICHousto]

I believe Rule 8, Sect. 5 B Note:

Should any act of interference occur following any obstruction, enforcement of the interference penalty takes precedence.

In my opinion, I would have the runner out on the interference and the BR would be placed at first base.

Let me spin this play in this manner:

R1 on 1st base. One out. Batter swings at pitch and is obstructed by catcher. Ball is popped up to 2nd baseman. R1 runs into 2nd baseman attempting to catch the fly ball. Since the interference has changed the "result" of the play how can you allow the OC his "choice"? I would have a dead ball on the interference, R1 out and BR out on the assumed caught fly ball. The rule book also stipulates that if the interference prevents a fielder from catching a routine fly ball, fair or foul, with ordinary effort, the batter/runner is also out.

As for the OP, I would have interference with R1 being called out and the BR being placed at 1st base. Catcher obstruction goes away.