Rage i like the start of your theory...my only thing is that they couldn't have known about red lyrium until after Meredith's crazy ass and Kirkwall. So if they started in on it...then too, who even suggested they start that? How did Coryphallis even talk them into...ohhhh. just answered my own question. i don't want to spoil the game in case someone still hasn't made it to the end.
i assumed its like the coke trade word of mouth and lucky break after she went statue. They had to dispose of her somehow and i think thedas lacks CAT4 biohazard containment proticals so as sick its sounds... free lyrium if they started mining her