Breast-feeding Adults: Explanation of the Hadith of Salim

I have come across several authentic hadiths about breast-feeding adults, and I was hoping that you can help me to fully understand the meaning.`A’ishah (may Allah be pleased with her) reported that Sahla bint Suhail came to Allah’s Prophet (peace and blessings be upon him) and said, “Messenger of Allah, I see on the face of Abu Hudhayfah [her husband] (signs of disgust) on the entrance of Salim (who is a servant) into (our house).” Whereupon Allah’s Messenger (peace and blessings be upon him) said, “Breast-feed him.” She said, “How can I breast-feed him, as he is an adult man?” Allah’s Messenger (peace and blessings be upon him) smiled and said, “I already know that he is a young man.”I also read authentic stories that `A’ishah, the Mother of the Believers, took the above hadith as a precedent for whatever men she wanted to be able to come to see her. The rest of the wives of the Prophet refused to let anyone come in to them by such nursing.Some people are attacking Islam and are saying horrible things about `A’ishah (may Allah be pleased with her) based on the above hadith, and they claim that the Prophet (peace and blessings be upon him) would never allow a shameful act of a woman breast-feeding an adult. They also reject the claim that Sahla didn’t physically breast-feed Salim but that he drank her milk from a cup by saying there’s no authentic proof for drinking from a cup and Muslims interpret things whichever way they want to avoid controversy. I realize that the above are misconceptions to raise doubts about Islam, but I honestly don’t have access to any authentic information to explain this hadith. Can you help me understand the meaning and significance of the above hadith and clarify any misconceptions about it?