It was confirmed that Marbury shouted loudly about how he was going to "fuck Thomas before he fucks [him]." This was his final stand against more time on the pine. It's unclear how awkward this was for potential replacement Nate Robinson.
Presumably, his ammunition for the extortion had to do with Thomas' "relationship" with Knicks executive Anucha Browne Sanders. As you know, we all knew out about that eventually anyway. That season's edition of the Knicks tied the franchise record for losses set two years earlier by the Marbury-Larry Brown connection. Isiah Thomas was let go and Marbury was gearing up for Knicks coach number three.