Death is the card of transformation. The Doctor appears quite contemptuous of those who would prolong life artificially, perhaps even more so because his own race did just that. He is like the Mummy, a soldier kept alive by ancient alien tech, yet his war never ends. The Foretold brought death to whoever saw it. The Doctor usually brings quite a lot of that himself. Perhaps he is unintentionally cruel because he does not understand the fear death brings. To him it is a gift. A man who cannot die might very well come to envy those who can. Once again class rears its ugly head in a Doctor Who story. The passengers on the train are of the intellectual elite doctors, professors and scientists. The kitchen workers are deemed worthless and expelled out the airlock. Gus is the truly heartless one for it values only its own agenda. Everything and everyone else is expendable.