This is part true, but mostly untrue.
If you start up an RX8, move it 2 feet and then stop the engine, you dramitically increase the chance of flooding the engine (for the reasons described by crabacle above). It’s not a certainty though. That said, it is strongly suggested you don’t do that.
You don’t have to go on a 10 mile run to avoid the problem though (although it might be fun).
How to minimise the chance of flooding
1 - If the temperature gauge is in it’s normal position (normally there after ~5 minutes of driving), then it’s highly unlikely the engine will flood. So don’t worry about it.
2 - If you need to move the car a short distance when it’s cold (it’s ok when it’s already warm - see point 1), sit there and enjoy the music/engine/exhaust note for a few minutes until the temperature gauge begins to move. Once this has begun to move, it’s highly unlikely to flood.
3 - Follow the shutdown procedure (although generally option 2 is preferred). There is a leaflet provided by Mazda with the newer RX8’s that covers this.
4 - Go for a short drive (couple of miles). Preferably down some twisty country lanes. That should warm both you and the car up.
I’ve personally followed these guidelines for the last 3.5 years, and haven’t flooded the engine yet (now touching wood).
If the worst does happen and you flood the engine follow Mazda’s guidelines initially (described by crabacle above), and if that doesn’t work try druck’s solution (above).