Jenkins made the absolute correct play there, especially considering it was in the 4th inning. You give up the run, and use the next 6 times you bat to make up for it. The last thing you want is to let it drop foul, then the batter gets a hit or reaches base and opens up a big inning. Take the out, give up the run, move on. Now, if it's the bottom of the ninth as you propose, and it's a tie game, you let it drop if you know it will land foul, and if you have less than a 50% chance of throwing him out in your mind. Here, you then have a better chance of your pitcher working out of the situation, plus if they score, you have no chance to win. If it happens in the top of the ninth, it's a little trickier because you do have one more at-bat, but if you let it drop foul, you're still risking opening up the floodgates