I think what the agreement was crafted to deal with is the possibility that Matt still isn't willing to admit he flat out concocted a story, that he will continue to alledge a tape exists or once existed only he no longer has it in his possession, therefore he will be required to either retrieve and produce it or provide credible evidence of it's previous existence AND evidence that someone on the staff either saw it or requested it be made or it becomes a he said they said where he loses the credibility battle. They won't say he's lying (unless they also have compelling evidence that proves he is doing so knowingly), but they also won't accept his allegations merely at face value.
Of course he may also come clean and admit the walkthrough story was a creation of fancy born of opportunity but I'm not holding my breath.
BTW knowledge of the walkthrough tape story's existence predated knowledge of the signal taping (because nobody anticipated the value of the signal taping revelation until after it occurred...who'd a thunk it'd be illegal to tape something in plain sight...). Felger has stated that employees of both the Herald and Globe had been in contact with Walsh over a couple of years - contact he initiated sometime after he was fired. If that is true then he only always wanted to get even and make it look as if he was fired because he knew too much... He likely wasn't looking for money which would have necessitated producing the tape, he was just looking to get even by giving an already distrustful local media (in what remained his family home town) a little something to fuel that distrust.
I don't doubt that when the video taping controversy erupted in September, his name wasn't passed on to some 4 letter turds so they could do the dirty work and connect the dots if possible. It was too volitile a connection for the locals to run with and they don't have the resources of the 4 letter network to camp on Walsh's door 6000 miles away. Even for them it was still a stretch even after Specter poked his stick into the nest. But that was reason enough for the NYT and ESPN to take Matt Walsh's existence public as well as his insinuations that he had more damaging evidence he might be persuaded to share (the old signal tapes).
I believe that in turn spooked Tomase, who I believe decided to mischaracterize a source into confirmation. I've heard that source was the lone employee who had remained in contact with Walsh after he was fired. He could confirm for John that Walsh in fact was alleging he taped the walkthrough, although he had no direct knowledge beyond what Walsh had told him, had never seen a tape nor did he know if anyone else on the team ever had. Under pressure and at risk of losing the real potential smoking gun story, and one most of the locals probably in fact believed was true just because it played to the cut throat image they held of Bill, John and his tabloid bosses who already had an exe to grind with Bill over access ran with the story before someone else decided to.
I don't think Walsh believed he would ever have to produce the tape. Pathological liars, including some I've known, never seem to consider someone will make the effort to disprove them. Even after the story broke, I think he believed he had enough other tape that he could somehow explain away an inability to produce that particular tape while still retaining credibility because he had so many others. Once he and his newfound handlers realized that the older signal tapes were of no use because the team had already copped to them and that was included in the penalty, he was effectively screwed. And now there was a friggin' senator involved.
This agreement is all about covering his ass and paying his formerly pro bono lawyer for nothing but this agreement. If he's smart he will tell the truth. If his ego won't allow that, he will tell his story absent any tangible proof and hope that they haven't already found a way to not only disprove it but to prove he knows he's lying. And that is likely what Spector and the mediots who got played by him are certainly hoping. They can live with lets all just walk away because of how they could then spin that, what would really harm them is if he admits the truth is there never was a walkthrough taped.
