He files away 'attuned to the Song' for further research later.

"So currently you have no known way to propagate your species further. Only speculation." He watches the water cascade between his fingers as he scoops a bit of warm water into his palm. "I've been thinking about that, as the last one of my collective. There's other Illithids belonging to other Elder Brains but they'd kill me on sight so I wouldn't consider them to be anything to me. Should I want more of my kind, I'd have to spawn them myself, and ... I don't think I want to do that."

The way he says that sounds like he's admitting some dark secret rather than saying he doesn't want to responsibility of repopulating his colony.