I don't see the need to put Bowden at risk there. Let him have his 2 perfect innings, which is more than you could reasonably expect from a rookie anyway, and go to Saito, who's fresher. It's good bullpen management not to ride guys into the ground, especially if you might need them later.
Besides, Saito isn't exactly overworked. He last pitched 2 days ago and was fresh and available.