No it is rust lots of steel on a GM in that area for the overhead truss to hold the engine up I would check it very close being that area is almost impossible to repair he needs to check the roof line at the back if the rivet heads have rust he should pass on that one IMO
Lol I take it you never saw a 4106 on the side of road with the engine dropped on 1 corner, I have saw several go to the scrap yard because of rotten trusses
I did like the beam idea