Hi,
Maybe your husband is feeling lonely and needs to talk to people.Although I don't know you or your husband, I am an ambivert and there are days where I could really use a nice chat. It really brings a smile to my face and makes me feel connected. If I may offer a free piece of advice to you, please chat with him casually for at least some time every day and encourage him to make friends who are like him. This will help him a lot and keep you both happy and hopefully, he won't have to go to extreme lengths just to say "hi" to people. Whatsapping and chatting on the internet with friends or relatives are also good ways to communicate with others and is refreshing and relaxing to people who like a nice chat! Hope you don't take this the wrong way!!