Robin is going to take the lack of a question as a "no", deciding to face straight ahead and lead the way rather than letting Phalanx lose his very expensive trinket in one of his hundreds of pocket-folds.

"It does look a bit like that, doesn't it," he goes on, musing partly to himself, "Though people here haven't quite caught on to that third one, yet. Radium, what a word..."

There is a light at the end of this tunnel, and not just metaphorically--the thin, pale glow of a lantern marks the approaching split in the path. When they get there, he leads them the left way, up a flight of stairs.