you hit the nail on the head here. they aren't saying that repitles are actual losers! they are saying that reptiles didn't have "species explosions" like other groups. other groups split up and made many, many species. coral reef fish are an excellent example!
you guys need to quit reading into things the worng way! they are simply saying that, evolutionarily speaking, reptiles didn't do all that well. they maintained but didn't split up like the other groups. they are talking in the now! not the past! don't forget that the world was once ruled by reptiles! that part was left out of the study as they are talking about animals today!!