Well, I don't know if the dev "ripped off" the designer...5 BTC for the design work we see here....way too much! If the dev were giving away 5 BTC of "OUR" money for this design work, I'd be disappointed. Think it was a misunderstanding or something else like that....The designer was paid; he just wanted more.
That reason doesnt really make sense when you think about him deleting the posts when the designer was asking about it for 3 days and then coming up with this "I paid partially story"
Just my thinking.. why delete all of that information if it was something so simple.