Reveal other player's Champions and Mastery Score
Well, first of all I currently have a very very slow internet connection at my area if that is related.
So, when I search for any summoner I can see his top champions, match history..etc, and as expected the champions tab is deactivated, however, when I click on my profile button then quickly press on the champions tab, I can see all his champions, golden frames, mastery level..etc. I can post a screenshot of other player's champions' screen if needed. I know this should not cause problems but I do not think you intend to allow player to see each other's champions and mastery score.