I'd say that if he didn't take the job and the Pats D takes a step back next year then he might have wasted his shot.
But we also live in a world where random guys like Vance Joseph and Kliff Kingsbury get offered jobs out of nowhere, so who the hell knows? Resumewise, you wouldn't think the D-coordinator of the 30th ranked team with only one year of experience at that level would merit a job, but Mike Vrabel was that when he got tapped by the Titans.
All that's to say, I have no idea what criteria teams are using to judge candidates. If he gets offered the job and it doesn't seem fishy for whatever reason, I'd think he'd have a hard time saying no.