That doesn't make sense at all.
Sora's heart was(and is) connected to Ventus, not to Vanitas. Vanitas only gained Sora's looks due to his still remaining connection to Ventus.
Ven's heart went to sleep (or rather, was forced to) because it was so heavily damaged after the destruction of the X-blade the connection to Sora wasn't sufficient enough to keep it going.
The injury was worse than when Vanitas was created, so something more than the connection was needed.
It was Ven's connection to Sora's heart which allowed Sora to feel Ven's great pain and sadness after his heart was nearly destroyed in the ending of the Final Episode.
Riku even commented on it when he suggested to Sora what to do because someone connected to him is sad.
Sora then reaches out to Ven's wounded heart ("Can you hear me?"), which follows Sora's voice through their connection into Sora's heart where Ven then pleads with Sora to let him stay.
And boom goes the dynamite. Knowing Nomoura, he will come up with some lame excuse as to how Vanitas can return. (clone anybody?) And then the unversed come back! But couldn't unversed technically exist if somebody got UBER pissed about something? The Unversed are manifestations of anger and hate pretty much.