Nope. It's actually very clear. Barry proposes the slowing down time stunt. Clark says, "You both die. When I opened the Book, I watched both of you die, doing exactly what you're talking about." Then there's an insert image of Barry and Kara burning up and disintegrating while attempting the speed maneuver. Oliver leaves and goes straight to the Monitor, says, "I know what happens to Barry and Kara," and makes the deal to prevent it. I think the knowledge that Kara and Barry die in the original comics Crisis (which is what probably inspired this bit in "Elseworlds") is distorting people's understanding of the plain text of the episode.