Why would you say that the switch from royal court to merchant port gives it a more SFnal feel?

Ah, yes, that is compressed beyond the point of making sense, isn't it? The line of argument, I think, was that classic heroic fantasy = medieval, therefore shift away from pure medieval feudalism to renaissance bourgeois society ("bourgeois" in the etymological sense, growth of the towns, as well as labelling the middle - trading - class) = move away from a fantasy feel. And away from fantasy, in the opposition currently under scrutiny, means towards SF.

To which I'd better add that I'm not talking, at this particular point, about definitions or identifications, simply about the flavour of a particular group of books. And that many of my favourite fantasies are set in the modern world.