I'm in 2 minds about the article and case.
I feel bad for the guy in that he may not have known the guy was 13 and perhaps assumed anyone using the app is above the age of consent. It may be ignorant to believe that but not criminal. He was reassured by some other person too whoever he was so it's possible he was convinced of to believe the boy was at least 18.
Where I have a problem with it is I struggle to imagine a 13 year old looking 18. I remember how I looked at 13 and I couldn't even pass for 15. That said I haven't seen the kid in question and he may look really old/tall for his age. I hope the man who is suing really did believe he was 18 and wasn't some predator but it's kinda impossible to know.
Either way it's a nasty story what ever way you look at it.