Click Latest. There it shows the right thing... ...but also says "including results for @jhamby ritanium" and has a link "search instead for @jhamby itanium".

Click Latest. There it shows the right thing... ...but also says "including results for @jhamby ritanium" and has a link "search instead for @jhamby itanium". If you click that, then Top works. (Note my iOS Twitter app version is somewhat old, so I guess I can't guarantee that this specific sequence doesn't work for you.)