In Scrum, the goal is to have open discussions during estimation, where all team members, including junior developers, can express their thoughts and assumptions. The Scrum Master should encourage the junior developers to keep their estimations because these can highlight different perspectives, constraints, or assumptions that others may not have considered. This helps create a more comprehensive understanding of the work and fosters a collaborative environment. It also builds confidence in junior team members, allowing them to contribute more effectively and learn from their peers in the process.