This is an odd statement, at least at face value. After all, the rules of baseball are pretty simple. A team is allowed 25 active players at one time, rosters expand to as many as 40 in September (at least for this year), and the number shrinks back to 25 for the playoffs.
Moreover, Voit has been a decent contributor in 2019. The burly first baseman has 19 home runs and 54 RBI to go with a slash line of .274/.388/.481. With the Yankees at 93-50, second only behind the Houston Astros for the best record in baseball, all signs should point to Voit being on the postseason roster.