Yes he does - not directly but clearly alludes to Earth being destroyed as they are suiting up to go to see the Engineer. He says something along the lines of 'sometimes things have to be destroyed before they are rebuilt' - something along those lines.
You are referring to conversation in Engineers cryochamber. So that's it? we are to presume she sacrificed lives of everyone because of one very vague sentence which David based on 30 second animation (which none of them actually see)?
Oddly, by that time she seems to have her mind made up already. She tells Wayland when they meet for the first time "This place isn't what we thought it was. They aren't what we thought they were. I was wrong. We were so wrong. We must leave." And that's even before Janek pops in, to jump into his own wild conclusions.
It does annoy me - the amount of so-called issues and plotholes in this movie seem to stem from people forgetting what was said, character intentions/beliefs and generally just switching off during the movie.
Bad narration and bad scripting just cannot be excused in this story. It could be that I come from a different generation, where even in fiction, character needs proof before they wipe the entire crew, but on the other hand, it's not like Lindelof is known for watertight plots. He likes his Lost type drivels, where he bombards the audience with "tada!" and "watch out" moments and then attempts to tie half of the stuff he threw in audience with vague one liners and "what if it didn't happen". no one does stories like that. That's not scripts are done.
It's fair enough if he does it in his own tv sandbox, but this is Alien franchise. People live for these movies. This movie, with those visuals, deserved to be legendary. It deserved to be written properly, full of characters we cared about, cheered for, cried for, watertight, well paced plot. We didn't need 17 crew just to not know what happened to most of them, we didn't need five types of sea monsters and twenty different plots free falling in different directions.
There is a difference between leaving things vague and stories untold and creating plot holes and annoying inconsistencies. Space Jockey in Alien, that's how you set up mystery. We didn't know who he was. We didn't know where he came from. We didn't know what his mission was. We didn't need to. And the movie was better for it. Making a movie about Space Jockeys and leaving audience none the wiser as to who they were, where did they come from and what their mission was, that's just screwing with the audience. It doesn't create "gasp" moments. It creates "WTF!" moments.
We deserved better.