Yes Nik was already a Cav for a short period of time, but after being traded to the rockets, and then the Pacers, and then waived, he signed with Cavs for the rest of this season.
Interesting that this doesn't violate the Big Z rule. For those unaware, once you trade a player and that player is then waived or bought out by his new team, he's not eligible to go back to his original team. Since the Cavs are were twice removed from being the original team, he was eligible to sign with them.
This is probably Nik's best bet at staying in the league. He'd get almost no playing time for any playoff team like the Pacers or Rockets. He may get starter level minutes on a severly tanking team like Cleveland.