I'm a lawyer myself, so in response to the prior comment on there being no reason Matt Walsh can't talk, I can tell you first hand that the lack of a confidentiality agreement in no way guarantees that a very rich man and very large organization can't make your life a living h*ll for telling the truth about them by dragging you through the mud (as the Pats and the League have already tried to do--that Boston Globe puff piece and the ex-FBI folks the NFL hired to investigate Walsh's background come to mind) and possibly suing you anyways in a spurrious defamation action that you'll have to spend years and hundreds of thousands to defend. You know what I just wrote is all true--your homer glasses just won't allow you to see it. For a literary version of this topic, try reading "Atonement" by Ian McEwan (or check out the recent movie.)
By the same token, this doesn't mean that Walsh has the goods on the Pats, but we need to hear from him what he has so that we can judge for ourselves whether it's credible or not. Again, I defy anyone here to argue with that logic.
Lets turn this around then. Why would the NEP ever give Walsh the ability to speak without any recourse against him if he lies?
Also why would what he says make him credible or not? Shouldn't you know if he is credible or not now?