All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
This hadeeth was cited by Maalik in Al-Muwatta’ from Ibn ‘Abbaas but we did not find any scholar who elaborated on it with a comment such as yours. If this act contradicted the forbiddance of divulging the secrets of sexual intercourse, or if it contradicts common sense, then Ibn ‘Abbaas would not have asked this slave girl about it.
The hadeeth which was reported about the forbiddance of divulging the secrets of intercourse was reported by Muslim from Abu Sa'eed Al-Khudri who said, "The Prophet said, 'Among the most wicked of people in the Sight of Allah on the Day of Judgment is the man who has intimate relations with his wife and then divulges her secret.'"
An-Nawawi said:
"This hadeeth is evidence on the prohibition for a man to disclose what happens between him and his wife of matters of sexual enjoyment and describing the details of that, and what the wife says or does during intercourse. As for the mere mention of sexual intercourse, then if there is no benefit in it and there is no need for it, it is disliked because that contradicts common sense ... but if there is a need for it or a benefit, such as when the husband is reprimanded for refusing to have sexual intercourse with her, or when she claims that he is sexually impotent and the like, then there is no dislike in mentioning it, as the Prophet said, 'I do that (i.e. having sexual intercourse with one's wife and parting away [without ejaculation]) with her (referring to his wife, 'Aaishah )...' He also said to Abu Talhah, 'Did you sleep together (with your wife) last night?' (And he supplicated Allah to bless his offspring). And he said to Jaabir, 'Al-Kays Al-Kays (meaning: Intercourse! Intercourse!).'" This was after Jaabir had been absent from his wife for a long time.
Allah knows best.