It would be nice if the list of riders could grey out anyone with a 0.0 w/kg and then hide them after, say, 30 seconds of idle time. Keep them listed as logged in somewhere, like the iOS app, so they can be found, just not in the active rider window.
And possibly have their virtual riders not on the road. When they starting and not pedalling they could be in a starting coral or when they stop pedalling after their ride has started maybe they could pull over off the road instead of stopping in the middle of it.