Can't you just search the page for them? Ctrl-F on pc, Find on page via Google search bar if you're on safari on the iPad, put the poster's name in and you can step through all mentions of the name, so you get replies that namecheck the poster as well as their own posts.
Oh, SandWitch, I agree. It would be especially useful when there is a conversation going on and someone says 'SandWitch I agree with your last comment'. I could then highlight all comments by SandWitch and know what that comment was.