I love the picture in my mind of you on the floor sniffing around Diesels ears!!! Us Yorkie people sure are a strange breed of people aren't we ? Personally Diesel sounds terrific to me,he likes people and is great with animals. Just like a child that clings to Mom's leg.
Give him his own time and keep taking him out with you so he is around people more,he isn't doing anything wrong, just shy .Love to see a picture of him