As others have already said Perk was not going to resign here... period. We could not have kept him beyond this past season. Remember he was actually given the choice to remain and he declined it.
Danny may have let him leave, but Perk talked repeatedly about wanting to remain in Boston, and seemed interested in taking a deal in the area of 4 years, $30 million when it was mentioned by the media. He ultimately signed for a bit more than that in OKC, but I get the impression that Perk would have stayed if Danny wanted him back.
I think a lot of fans draw way too many conclusions from Perk's rejection of the 4 year, $22 million contract that Perk turned down. That was a lowball offer mandated by the rules of the CBA; the team could have offered more this summer. Nobody, including Danny Ainge, thought the offer the Celtics made was Perk's fair value, and fans shouldn't draw conclusions about Perk's willingness to play in Boston based upon his rejecting the offer.