This little turbo (meaning the impeller is about the diameter of a half dollar) is done spinning moments after the engine returns to idle, so it can be assumed the bearings aren't spinning and oil flow is of no concern.
The next thought though is cooling the bearings by allowing the engine to idle momentarily, causing the oil being pumped to the turbo to pull some heat off them.
Although nothing is written, and many feel the 'cool down' is unneccessary, I'm old and therefore, old-schooly in my thoughts.
As a result, I let it idle a few moments while turning the fan off, turning the radio off, get my wits about me before shutting it off.
I figure thats long enouph, maybe thirty or fourty seconds, to assure the turbo bearings had some heat pulled off.
Regardless of my thoughts, I don't think anyone on the forum has had a turbo failure related to bearings....just a couple of worn out by-pass links......so....its up to you to decide how you want to go through a shutdown but I suspect I likely lean towards overkill.
Rob