He said "The A's played 54 of their 60 games against teams that finished below .500" not teams who were at or above .500 at the time. He is absolutely right it took me 2 minutes to fact check.
10 games against Astros (.483)
10 games against Mariners (.450)
10 games against Angels (.433)
10 games against Rangers (.367)
6 games against Giants (.483)
4 games against Rockies (.433)
4 games against D-Backs (.417)
3 games against Dodgers (.717)
3 games against Padres (.617)