That's an interesting reading of the former employee's story. According to his post, he entered into a consulting agreement with Opera in 2009 and between 2009 and the time his agreement was terminated in late 2010, "some of my design proposals will naturally be based on some of my older GB concepts."

I don't think anyone has enough information at this point to pass judgement on the merits of the case, but at a minimum, this looks like a pretty good example of what can go wrong when you involve ideas you've developed on your own in a consulting relationship, particularly when there's a chance you may want to further explore those ideas after the relationship ends.