I don’t know about it being twisty just for the sake of it, well maybe the ‘Luke is really Vader’s kid, he’s not Skywalker Sr’s son’ concept can be said to be twisty for the sake of it. The Anakin killing Vader then taking Vader’s identity twist perhaps would mean not so much a family bloodline story but more of a ‘Darth Vader is not who you think he is’ type of story. And it does change things, especially if it’s a bit of subterfuge where neither the Sith, Sith Master, The Emperor, or even Ben Kenobi knew the real truth. And, if the story is/was true, Lucas did eventually drop the idea anyway before even beginning to write the final draft of the script. I used to think perhaps Kurtz had an alternate take on the twist, but in the quote(s) he still maintains that the twist that we’re all familiar with didn’t come about until the second draft of Empire (ESB). This would mean that instead of the truth confirming Lucas’s often made claim that Vader was Luke’s father when they made ANH, it would mean that at best, Lucas toyed with a variation of the twist idea before dropping it and going with the Vader-killed-Luke’s father story. An idea which if you think about it, almost sounds like a mirror-reversal or flip of the ‘Anakin-killed-Vader’ idea. One could also say that the twist that Empire brought about was Lucas’ older dropped idea but having been run ‘through the wringer’ of the concept of Vader having killed Luke’s father, where everyone - Sith, Empire, Ben Kenobi were all in the know, but now a literal killing being re-cast as a metaphorical killing (and the ‘certain point of view’ aspect being added in the later drafts written for ROTJ).
I don’t think one necessarily automatically contradicts the other, depending on one’s perspective. To Lucas, as an example, that he was toying with the idea may be enough for him to say it was planned out, in theory. Or he could be just being exaggerating. I dunno.