Pao is like that too and he is going to be six in June. When I invite people over, I just let him be. When I am busy ie cooking, I just put him down and tell him no when he wanted to be picked up and eventually, he will go warm up with the guests he likes and asked for scratches.   
I don't really bring him to friend's house since I don't like the endless possibilities of dangers of having kids running around since he isn't kids friendly.        |