Throughout the entire process, Sam didn't interfere with Zoe's handling of the situation, nor did he have any intention to.
First off, it wasn't appropriate; after all, it was a matter related to Zoe's work. Why should he meddle?
Moreover, he was curious to see how Zoe would handle such a situation. Instinctively, he felt that Zoe wouldn't be as 'lovestruck' at work as she was when she was with him, but to his surprise, her performance was even more impressive than he had imagined.
She was incredibly assertive. Was this really how she treated her business partners?
She wasn't overly aggressive, at least she didn't curse out loud. But she managed to clearly convey a message: "I'm not very close to you, and I don't want to see you on my day off."
It was refreshing. Incredibly so. Especially her indifferent tone, Sam believed that anyone with a brain could sense what her attitude was.