ANSWER:

Of course he is sinful!

He must have stepped back and not allow her to touch him, let alone hug as Prophet ﷺ said its better to be stabbed in the head by an iron needle than to touch a non mahram 

QUESTION: A brother said he went to visit an elder relative and his non mahram wife approached him and hugged him (he didn’t step back or prevented her)… she sees him as a grandson also saw him growing since a kid… He’s asking if he’s sinful?