Hello all, and thanks in advance for the opinions and help. The vehicle in question is a 2020 Civic Si sedan.

Had an insanely loud rattle for the past couple months, finally took it in to dealer assuming it would be something loose in the trunk area and be repaired under warranty. Dealer found that the passenger side shock/strut mount was missing a bolt where it attaches at the top, to the body of the car, and that the "body welded nut has broken free". Photo below.

The tech's advice was to take the car to a body shop where they could cut out the mounting area, re-weld the "body welded nut", and then reweld the removed section. "Found right rear shock absorber was missing a bolt. Where only 1 bolt was holding the shock, the body welded nut has broken free from the body. Installed the shock securely with 2 bolts for the time being. Customer should visit body shop to have the repairs to the body welds done."

Questions:

1. In my research, folks have stripped the threads in this area, and just re-tap for new threads, indicating that the flange bolts attach to threaded holes in the frame/body of the car directly. I also can't find any parts diagrams or anything showing how the flange bolts actually attach to the car. Is there, in fact, a body welded nut on the other side of the body?
2. If so, is sending to a body shop the right approach? Surprising that Honda didn't envision some way to make this repair, given it's an area of major stress where the forces from the road are transmitted... but then again, I suppose this is a pretty uncommon repair to need to make.
3. Any other thoughts or things I should think about?

Dealer: "Black is the area where the body will need to be detached and rewelded, red is where the missing nut is."

 

That should be a manufacture defect and covered by the dealer.