That is an incorrect hadith, there are many weak sources about aishas real age at the time of marriage. Also there where muslims in history who tried to turn prophet muhammad into this salacious person that thinks of sexual pleasuring all the time so they get their allowance for their wrongdoings. Sharia law is just trying to apply the rules of god for muslims in a muslim society and that's about it. In the actual authentic Islamic history, Aisha is 10 years younger than her older sister Asma, her sister was 29 at the time of her marriage which means that Aisha was 19 at the time. Before that she was only promised to the prophet. In islam you can not become a muslim unless you are relatively mature which is like the age 9 in islam, Aisha was 7 when she came to islam and was betrothed for marriage at the age of 17, 10 years after the time when she became a muslim, she married the prophet at the age of 19, two years after she was betrothed to get married to prophet muhammad.