Unfortunately for him Jai's a kind of running joke in the talkbacks of a few big movie sites like AICN and /film. As in 'if you want to screw up the movie cast Jai cos he cant act for s***'.
Why Forsyth would be in-the-know about casting of the role is beyond me though.
I can think of one good reason - he's been in the spy thriller business longer than most of us have been alive. It's completely conceivable that he'd have rubbed shoulders with Cubby etc and still have a few connections.
Also, he sometimes does the msn/tv show political opinion circuit and whether or not one agrees with his pov, he's definitely a straight talking - no BS kind of chap. So imo he's a decent source.