Maybe so, but the fact is, it works. If there is no stick movement and you just let the TX sit there, the module will get really hot. Aslong as you're using the TX and transmitting moving signals, the module stays within a reasonable temperature. I'm not saying what I said is accurate, as i'm not an electronics engineer, but this is from my own personal experience and what i've been able to gather from other sources online.

If the antenna isn't fully extended, the module will also heat up, regardless of present stick movement.

Maybe it has something to do with transmitting differnet signals instead of the same one over and over? I don't know