First off, thanks for calling me a tool

Second, a sudden back spin can do a couple of things [besides all of this, a BOV won't matter if you're not in boost to begin with, but how often can you merge on the interstate without a heavy enough foot to get into boost....]. Bearings get used to spinning in one direction, and the oiling system in a turbo is another you need to consider, and not just the robustness of the turbine. Not only does the engine force oil to the turbine shaft to keep it lubricated, but as the turbine shaft spins, it helps feed oil though so that it can go out through the drain. By back-spinning a turbo suddenly you can see an oil pressure spike that can lead to failure of the shaft seal.

I've seen it happen several times, and the damage gets to be quite expensive, so yes, I compare it to destroying a perfectly good transmission out of stupidity.