I don't see why the delays would scale linearly with travel time. I would naively expect them to be a constant. So geosynchronous satellites have 240 ms of travel time and 310 ms of delay, in which case we might expect LEO satellites to have 13 ms of travel time and 310 ms of delay.

Maybe it's not that bad. Maybe you have to use more robust coding with geosynchronous satellites, and that drives up latency. But i can't see a reason why it would scale linearly with distance.