I don't think Rondo wants to leave, I think he wants the team to make a commitment. Ainge tried to trade him multiple times. And he's still not taking him totally off the table.
If Rondo could sign a five year extension now I think he would, but the CBA only lets him sign one for three years, which he's not going to do. He's going to be 28 or 29 when he signs his next contract, which will also be his last big contract. I don't know if he wants the full 105 million dollar max, but he's going to want a big contract, especially after playing at such a discount on his current one. He's going to want five years, and I have a hard time believing he won't ask for a no trade clause.
I'm biased because I like Rondo, but I don't see him planning on leaving. I see someone who knows what Ainge is like and doesn't want to let the narrative of his free agency get out of his control. He wants to negotiate on his terms.