If the pro lens was capable of interfacing with the brownie, you could take some outstanding photos with it, as rediculous as that may seem. The brownie functions simply as light-tight box, shutter and film advance. A fully fuctional professional camera body has more advanced functions and controls, but by far the important basic element beyond a simple shutter and light-tight box is the lens.
It is most certainly a rediculous combination for a professional who requires reliabillity above all else, a streamlined production environment, has use for advanced controls, etc.
But it is not a rediculous combination based soley on the potential quality of the end product, the mis-match does not prevent it from working, just eliminates 'niceties' of getting the job done and reliabiltiy, which are critical for a professional for hire.
I once attended a exhibition of beautiful large-format photographic prints made with various high-quality professional lenses mounted on cardboard boxes, the filmstock simply adheared to the back of the box and the lens cap used as shutter. Basically a homemade pin-hole camera with top-caliber lenses attached, not nearly as advanced as a Browine!