I am not aware of any book-length biography of Farina, so I can't be sure how active he was in the early 1950s when he was approaching age 60. But my guess is that he was still heavily involved styling the cars his company built.
Which brings us to the strange 1952-55 Lancia Aurelia PF 200 (where PF = Pinin Farina), a Lancia model B52. A little background information can be found here and here. It is pointed out that the PF 200's styling seems to have been inspired by jet fighters -- the almost-round grille opening looking similar to nose air intakes of the Russian MiG-15, the French Dassault Ouragan, the American F-84 Thunderjet and others.
Farina, it seems, was temporarily afflicted with the same disease as Detroit stylists. Car design having evolved from collections of discrete items (separate headlights, fenders, trunks, hoods, etc.) to all-encompassing "envelope" bodies (the 1949 Ford, for instance), stylists began looking at jet fighters, science fiction space ships and even insects for inspiration. At this time, Italian designers tended to treat automobiles as automobiles and not rocket ships. However, they did stray from time to time, and the PF 200 is a good example of that. At least only about half a dozen were ever built.