I hope you don't mind if we comment on this thread to possibly explain our side of the situation.
Initially we received an email from our dealer TH saying a customer had a coilover set that had a nut that we welded on, i stated that is not possible an we needed pictures. After receiving pictures i confirmed the nut was not welded and looked in fine condition and we instructed them to have customer call us directly. I received a phone call from a person regarding this situation. I know OP says it was the shop, but she stated she was your wife and not a repair shop. Yes i did state the nut should not be removed to her as i was confusing this application with the Mazda 3, but with over 1000 products developed its really really difficult to remember the particulars of each one off the top of my head, hence the reason we requested the call back before we came to any conclusion as to what happened here.
Regardless we are not sure why the shock was so damaged removing a nut. The nuts do not have locktite (we would love to speak to the mechanic that stated this as there is no way this is possible since we do not even have locktite on the assembly line), they are nylon locking nuts, which are designed so they do not back off while on the vehicle, a very very standard nut. This is a non-issue when removed with an impact.
If there is every any defect of cource we would take care of it, we do not sell over 5000 coilover systems per year by having poor customer service and screwing over people. But when we hear the nut is welded, than it was cross threaded, than there is locktite, all of which we know is not possible we tend to think possibly there was installer error the mechanic is trying to push blame on us. Hence the reason we requested to speak to the shop you said installed them, so we can try to understand how this was damaged. These nuts are designed to go on and off, over and over, but an impact is needed set to 45-50lbs. of torque, and its not possible to cross thread this nut on the shaft due to thread pitch and damage shown.