Runner on 1st doesnt leave base and is tagged before runner reaches 1st

Question
Mark - Runner on 1st (2nd base unoccupied) less than 2 out.  A low pop-up was hit in the vicinity of 1st base.  1st baseman could not make the catch - the runner never left the base and 1st baseman could not manuever around the runner to catch ball (ball landed directly at the feet of the runner on 1st).  Ball remained in fair territory, was picked up by pitcher who first tagged the runner currently occupying the base, then tagged the base to force the batter.  Umpire ruled that batter was out and runner was safe because he had a right to the bag, even though runner was tagged before pitcher touched 1st base with foot.  How do you see this?

Answer
Hi Mark,

I see this correctly and not the way your umpire saw it.

R1 has no right to the base once the batter becomes a batter-runner.  Tagging R1 anywhere except them standing on 2nd is an out.  Then the b-r was out by the touch at 1st.

This is not a difficult nor that uncommon a call.  The umpire should know better.

Mark