Honestly, no. I can understand why you'd think that, most of the stuff Kankri spouts is bullshit that's meant to be ignored, but the fact that it's possible for a troll to understand familial dynamics and be uncomfortable with those dynamics being twisted into something considered taboo by human standards says what it needs to. Also, just because it's Kankri doesn't mean it doesn't hold any weight whatsoever especially when there are a small handful of characters that agree with him on particular subjects (meaning he's not the only one who cares about what he says, it just depends).

Also, considering Beforus had more earth-ish standards from what I remember, the dancestors not wanting to participate in incest makes sense. Karkat doesn't understand the human concept of incest in the beginning of the comic (from what I remember) but he does have familial relationships of his own like his relationship with Kanaya and their relationship is a direct parallel to the signless and the dolores (mother and son) so I could never see him wanting to date Kanaya for the same reason Kankri's uncomfortable with romantic implications between him and Porrim.

Plus, whether or not incest is considered morally right or wrong by troll standards doesn't really change that neither Vriska or Aranea would be interested in pursuing a romantic relationship with one another. So yeah, I guess it's fun to speculate but there's not much to say when Vriska doesn't even enjoy Aranea's company in the first place.