And with Ristolainen gone (not yet, but everything is pointing at a departure in his case), and maybe Justin Braun, the Flyers will need a right handed defenseman next year. Petry, although he is 34, can still be a very valuable blue liner. His season with Montreal is difficult, but things were so bad right there that almost everybody on the team wasn't performing as expected.
Petry got three years left on his contract (at $6.25M per season), and even though it could be seen as a burden, the Flyers will anyways be in this kind of situation by signing a top 4 defenseman during free agency.
So, Friedman is right : trading for Jeff Petry makes a lot of sense for the Flyers. It all depends on Fletcher plans for the future, but if he recoups assets in trades involving Giroux, Ristolainen, Jones, Konecny and Brassard, it wouldn't be that bad to throw a 2nd rounder (and maybe a bit more) to acquire Petry.