I was able to re-find the now Siberian Blue Robin today, although it required my almost stepping on it. Once flushed it is extremely cooperative and easy to follow, but the initial flushing is tough!
Anyway, I paid close attention to the tail shivering. The bird essentially NEVER quit shivering the tail (and sometimes wings) the entire time I watched it. When hiding in the wormwood, when out in the open on the dirt, after being flushed and landing, the tail was constantly "shivering". I'm not sure how much shivering Rufous-tailed Robin does, but there is no way it could top what the bird was doing today.
Here is another picture from today. Tough to get good photos when the lighting is this bad.