Take a moment to scratch the surface. Jack started out as a warm human being, much as Sydney is now, and much of what he does is aimed at ensuring that
Sydney does not become what he has become. So, because of that priority, he makes mistakes. "Don't Trust people because they're nice . . . Meanwhile, a total jerk might risk everything for you." Think about that when you think about Jack. Jack has gone through a lot and become hardened as a result. He doesn't do things so that people will like him. He does them to get results.
On to Elsa Caplan. Ever hear the phrase "cruel to be kind"? Not only did Jack get the verification he needed from her in a short period of time, one brief but unpleasant experience allowed her to forego a lengthy separation from her family while the US govt determined whether she should be treated as a defector or enemy. And let's look a little deeper. Mrs. Caplan was playing it both ways, wasn't she? She fell in love with the American she was spying on, yet she kept on betraying his trust and working for her government. She wasn't willing to choose. What did she expect? That she could just go on pretending and eventually she'd be allowed to retire?! Sooner or later it was going to blow up in her face, but she was too much of a coward to make her choice and come clean. Instead, she waited until the endgame, when it was too late and she doomed her husband to death. She should get down on her knees to Sydney in thanks for her husband's life. Sure, I have some sympathy for her, but, come on! Swallows play a
very dirty game. The fact that her husband was aware of what she was doing and forgave her was not her fault but her good fortune.
Sure, I'll go that Jack has his jerk side. But, then, again, Elsa Caplan was no angel and deserved to be forced to take stock of her life. Seeing the situation from the perspective of someone who was in a situation like her own husband was probably a valuable eye-opener for her.