Maybe. It's a nice story. But I'm not exactly sure who was going to give him a better deal than that. Maybe he would've gotten a little more per year on a shorter contract, but I'm not seeing a long line looking to sign him.
He's a nice player capable of being a rotation player on a contending team; however, he's clear not anywhere near a star. Furthermore, if his other offers were so impressive and he really just wanted a shot to win here, I don't know why he didn't sign a 1-2 year deal and then test free agent waters again. Even a 3 year deal would've allowed him to re-sign here with Bird rights if he really loves Boston as much as he says.
I think the real story is that he was hoping that someone would offer him more than Boston gave him.