Is there any reason they wouldn't just make those independant panels and weld those joints? It's a little slower than stamping, but cutting and welding panels like this is well within the capabilities of their existing robots.
They are starting the cut and bend operations with the fully hardened steel, so there is no post stress relieving / aging / finishing. It's about as simple as it can get for metal fabrication.
Welding also fundamentally changes the underlying steel properties. I'm not up to speed on full hard 301 SS, but most likely any thermal operation will degrade it's mechanical and chemical grain structure.