From the failure to use a more proper expression; it's clear the writer was not thinking in terms of this guy being, or having been, Spock's father.
Of course, it can be interpreted that way. It just takes effort and motivation. And motivation is offered by later Trek ideas superseding/complementing earlier Trek ideas, as usual. Just like we get nameless domes in TOS and then learn in TNG that they are called Bussard ramscoops.
And it's only a retcon if you read in more there than what is there
Not reading that the writer of the first episode disagreed with the writer of the second one would be reading too little, turning a blind eye, whistling and pretending. Making the two pieces fit together calls for filing away some of what is being said, and filling in some. Of course it's a retcon, and a far more blatant one than belatedly assigning an identity to some unnamed feature of Kirk's ship.