Doesn't Galatians 5:22, 23 or something talk about the fruitage of the spirit? Do you see 'court victories' in that list? I don't.
Other groups, probably some of them religious, have no doubt won court victories too. Does that prove they have God's spirit? If they won or if they lost, it really doesn't prove or disprove anything. It just is. (As I hear it told, some JWs intentionally created legal problems for the sake of gaining public attention when they really didn't have to. But since that's hearsay, it's not a suitable argument.)
Think about the reasoning here. If the JWs lost those court cases, it'd be a case of satanic persecution. Yet if they win, God's spirit is with them. When you've already drawn the conclusion that God is with you anyway, there's no amount of reasoning that will change your mind.