Yoshida-san elaborated a bit saying that it's "very convenient" and we would somehow "super-charge the Echo" and avoid the need to die. Though I'd be surprised to find Elidibus outright lied. Don't get me wrong, I've believed since his first cutscene that he was a snake, but the assumption that he has never outright lied and merely speaks in vague double-meanings with selective omissions that lead you to make the assumptions he wants you to has been my guiding principle for analyzing his character. Finding out he lied would send me back to square one on him which is... <shudders> [beat] <shudders harder>