It doesn't seem like too dumb a move on their part, although it certainly is odd. However-

1.) Their T&C against rakeback remains intact. Party does not offer rakeback and never will.

2.) They get the high volume players back from the skins. Many would have returned at first for the soft games, but they'd head right back to their sweet rakeback deals if the skins somehow revived themselves.

3.) They get to show their shareholders that thousands of new people signed up.