If I am looking at someone else's activity on the iOS mobile app, and tap into a Segment they matched with, I only see my own position on the leaderboard. If I have no times on that segment, then I see just the Top 10, which isn't very useful information.
This does not match the user's expectation - since I am looking at my friend's activity, I should be able to see their rank on the leaderboard, along with my own to see our relative positions on the leaderboard. This feature would help me know how to encourage my friend (eg, they were in the top 1% of people on the segment, I could shout that out; if they were #11, I'd tell them to work harder next time..)
Note that this information is available on Desktop Web - on a friend's activity, I can see their position on a segment's leaderboard, and compare it to my own.