Agreed. They were doing CDS deals. Every bank I've worked at has their models in COM assemblies that can be consumed by Excel. Excel lets the traders value their instruments using the models. The inputs may have been copy-paste but I'd be hard pressed to believe that the risk numbers were generated by hand in Excel unless this was some very exotic instrument which I don't think it was.

Risk numbers aren't generated by Excel but an automated process that uses the same assemblies.