1. Her basic functions didn't work yet, so there was no chance she could do missionary, which is the only move Kim's mother told him about.
2. Seven knew Kim was a punk and she intended on scarring him off psychologically, without putting out.
3. If Seven planned on having lesbian sex with Kim, becuase that's how she liked to have sex, like a lesbian, hands, mouths and toys, then her out of order woo hoo and poo hoo amounted to squat. Instinctively in the third episode of season 4, Seven decided to be a top and Kim was her bottom... If he had stayed.
4. Maybe she was planing on creating a miniature collective with Kim, where all her sex organs were functional, and it would have unfortunately been straight vanilla sex after all?