Anyone who is upset about the whole "spying" angle who has never checked the story of a loved one, including for stupid stuff like chores and bills and the like, who has never once returned for an item they "forgot" to see if he's back playing that video game again as soon as you're out the door or talked to a friend about what the golf score really was, who's never taken a look at social/gaming media to figure out what they're doing when you don't feel like asking, or who's never flat out called someone out on their lie raise your hand. Yeah. Thought so.
People lie. People lie a LOT, for all sorts of reasons. About whether they really think you look fat, or whether that T-shirt you love makes you look stupid. About whether they're really happy today, or whether they can stand their inlaws. About how many beers they had last night, or how many video games they play. And sure, nine times out of ten everyone knows it's a lie, and just goes on from there... but to say that you trust people implicitly and would never check about anything is kind of insane.
Trusting people not to hurt you, not to cheat on you, that's different. There's lying to avoid an argument and then there's ripping your heart out, and if you can't do that the love's probably over. But not verifying something you think is fishy is just plain stupid, it doesn't make you morally superior.
As for legality? Well, I'm not sure how all this will play out for him. But laws aren't always right, and they don't always serve their intended purpose. The guy should be fine, legally... heaven knows he's got enough to deal with right now.