He could definitely know what went down with Han's family. Or at least know as much as your comfortable with him having obtained information over it.
Maybe at one point or a few, he managed to redirect the government from uncovering information about Arden? Arden could have found out and maybe they have some sort of unlikely friendship? ...or a civil understanding and respect of one another. James really worked hard against his former employers so they didn't find out most of what they wanted. lol