I'd have to disagree. What is the intent of copyright? If it is to prevent consumer confusion then I would have to side with The Tetris Company. I took a look at Tetrada and it is a clear duplicate, and if I was younger I wouldn't know any better and assume that this was Tetris. You have to take into account the sum of what you mentioned. If there was a game called Tetrada, and it didn't look the Tetris, then fine. However, you have a game that looks like Tetris *AND* a game name similar to Tetris.
Personally, I like this action. The 'indie dev scene' is being taken over by developers intent on copying others ideas to make quick profit. I suppose this was popularized by Zynga. Don't get me started on Angry Birds...