While the 49ers might not install the actual game plan until this week, there are still little tendencies from both the offense and defense that he could illuminate for the Packers' staff. In particular, he could speak to newly installed packages and some of the unscouted looks they intend to reveal, whether against the Packers or other opponents early in the season.
Just look at how the Packers have intermittently game planned for the season: they've allotted a good amount of time to preparing for the read option, and they've spent time installing packages that the beat writers are asked not to discuss with the public. I realize that the former is to be expected, especially given the QBs they face the first two weeks of the season, but the latter is the type of intel that Tolzien would be privy to and be able to share. Now, how helpful that information is overall is debatable. Moreover, it could be detrimental in that it results in them spending time preparing for looks that never materialize, thus devoting less time to understanding better looks that do. Who knows. I mean, look at how much McCarthy lamented the loss of Harris. It was clear that he had installed some packages specifically for him, and I'd have to imagine Coleman and Young would know about that in the same way Tolzien would know about some of the packages the 49ers have implemented, no?
The truth is probably somewhere in the middle: Tolzien can probably be helpful in some capacity but perhaps not too helpful. More importantly, though, that added information means nothing if the Packers cannot execute effectively and consistently the plays called on the field.