I am looking for some input regarding the following. A colleague of mine feels that if there is a problem or "perceived" problem on a delivery team it should be brought up in "public" in an iteration retrospective with the whole team?

Hypothetical situation: You have a talented senior developer who is an introvert and does not like conflict and when he sees a problem with another programmers code instead of providing feedback to the other developer, often a junior developer, he just fixes the code. So he isn't sharing his knowledge and thus not providing an opportunity for that team member to develop.

Let's say a scrum master is facilitating the retropsective,  should the scrum master bring this up to the whole team at the at the retrospective? Or is it more appropriate to discuss this with the senior developer individually first? I would think you wouldn't blindisde the developer with this at the retropsective unless you have discussed this with the team member and the lack of knowledge sharing is limiting the ability of the more junior members from advancing their knowledge and capabilities and is truly considered a problem?

Assume they are aren't on an XP team and they are not pair programming. But even so would this make a huge difference?

Ineterested in what the collective intellect and experienced agile practitioners say about this.