I understood the not wanting Aiden to speak to the guy downstairs as being about her knowing he would be doing it for trust reasons. She asked him not to speak to Duncan because speaking to him was going to be an invasive, suspicious grilling and she is coming to like/respect him and appreciates having him to work with. She didn’t want Aiden embarrassing her with his jealous probing, or doing mental shit like coming down and disturbing them when she said they’re working.
It reminded me of my XH who would take a dislike to a man I knew however vaguely, and would get embarrassing and heavy handed around them/me. Very overt and ridiculous and it infuriated me. One of the many reasons on the divorce list.