They weren't talking about HM, they were talking about normal. If you look at the Group Finder, you'll see Lost Island is in the normal mode Flashpoint list. So is Red Reaper. They were saying that Red Reaper is probably more appropriate for a fresh level 50 than Lost Island, so maybe Lost Island shouldn't be in that same set of normal FPs required for the random.
Or you could check only reaper and uncheck LI