I found it odd as well.
The advantage was minimal (Kirk's chance to get a game winning hit is just a bit less than Guerrero), but nonetheless it was an advantage with zero risk -- you needed to walk Guerrero there and take the small advantage.
If runners had been on second and third it's a different story - you go after Guerrero, since you are then comparing Kirk's ability to simply get on base (OBP) vs Guerrero getting a hit (AVG).
Anyway new game tonight and it seems like Yanks are squaring it up.