Actually, it is more. A geosynchronous orbit is 40,000 km, the speed of light is 300,000 km/s. The signal must travel back and forth twice for total of 160,000 km, not including ground travel and network latency. The travel time alone requires therefore about 530 ms of latency, plus the other factors, or a minimum of 600 ms latency.
If using 3G in addition, these networks generally add another 75-200 ms of latency, giving this upwards of one second of total latency.
Since RemoteRig becomes very difficult to use above 100 ms of latency (especially for CW) and often is unusable even on some 3G networks, I would not recommend using it via satellite.
73,
Mitch DJ0QN / K7DX