Honestly it's often shitty interaction for both the stutterer and listener. Different people feel differently about what they want from their listener in different situations. My thought, the default choice is to be patient and let them finish and by simply waiting it out, I would say you took the correct and responsible path. It's what I would want. I have people tell me, "it's ok" or "take your time" because they think I'm nervous. I don't prefer this, but more often than not it does help me (which annoys me even more lol). Bottom line is the best thing to do is to be respectful. You weren't sure what was best so you defaulted to patient listening. That's the right answer in my mind. Don't out pressure or guilt on yourself to make someone else's stutter easier. Beyond being respectful that's usually not something you can do. It just sucks the guy was having such a hard block that moment.