I have no idea how you could get that second interpretation from what he said. And the perspective is clearly inherited from the parent comment, who didn't ment

I have no idea how you could get that second interpretation from what he said. And the perspective is clearly inherited from the parent comment, who didn't mention being "on board" a bus, just "on the road with" a bus. No ambiguity in that comment that I can see. EDIT: I guess the use of rather in this context could be a colloquialism?