Spreading this meme, even by a believing virtue ethicist, would seem to reduce the lifespan of fat men with bounties on their heads much faster than it would spare the crowds tied to the train tracks.

U: "Ooo look, a way to rationalize killing for profit!"

VE: "No no no, the message is that you shouldn't kill the fat man in either ca-"

U: "Shush you!"

Of course, one may want to simply be the sort who tells the truth, consequences to fat men be damned.