As I understand it, some ace people find sex gross and obviously want to avoid anything relating to it it, but some are neutral towards it. If they are with a partner that likes sex, then they may enjoy having sex because it makes their partner happy. Or maybe they find the physical sensations enjoyable, but not looking at porn/people. Or maybe they just want to do it for good prostate health.

They are not contradictory because “I don’t like sex” (which I didn’t actually say) doesn’t necessarily imply “I dislike the idea of sex”.