OBR Rule 2.00 - FIELDER’S CHOICE is the act of a fielder who handles a fair grounder and, instead of throwing to first base to put out the batter-runner, throws to another base in an attempt to put out a preceding runner.
The rule doesn’t say anything about the score, the situation, who’s running, whether it was an ordinary effort, or anything else.
Once he fielded(handled) the ball, did he choose to throw to another base rather than get the batter-runner at 1st? If he could have gotten the runner at 1st and didn’t because of a CHOICE he made, it was a fielder’s choice.