Uh, no. The original workout was set up for being in the Falcons' stadium and did include media access. It wasn't open to all media, but there were several major media sources allowed in. The reason that Kaepernick's camp gave for switching venues at the last minute was that they didn't like the liability waiver that the NFL had presented them and that they didn't have certain specific media groups allowed in that they wanted there.
Regardless of whether their reason was legit or not, it does cast doubt on Kaepernick's desire to play for the NFL, given the fact that the practice went from being attended by about 11 teams down to 8.
It would not have been easy to "bury" good performance by Kaepernick, given the media access allowed with the original plan. Granted, I don't think the NFL had any doubts about what his performance would be like during the practice. As others have mentioned, they're more interested in seeing if he's willing to be a team player. The last minute changes to the practice by his camp makes it look like he really doesn't care about that sort of thing.