It makes sense
The responsible is what the leaders need to be, being honest, incorruptible, just, and so on - and as I think I have mentioned somewhere earlier, Gondor (and Arnor) are portrayed as places where the leaders more or less are up to this standard (no "Black Númenorean" trait here).
To that Gollum thing, I believe Tolkien actually did not know - maybe until the last part - what would become of Gollum. I don't know if he mentioned this in the letters, but even if he did, maybe he did know it "conciously", as a Writer, but not as someone who lived the story as it formed... as he himself is saying, "I didn't know what happened to Gandalf and who Strider was", so perhaps, even the fate of Gollum "just came" in the end; and if we consider the story "living", as the Professor himself definitely did, this is how Gollum acted - at that point. His choice, that's all.