There are some problems with getting the FA to work on a major campaign.
The biggest problem with it is that the FA works out in the open. The plotline is available for everyone to see. I've set up the academy that way because most of the people the Academy take on are very new to FRED. Some of them dabble with it a little and then decide that it's not for them. In addition I wanted people to just wonder past looking for a mission to play and do some playtesting for us.
As you can see this is fairly different from having a mod team who are more likely to be there for a long while. Plus you don't want the hassle of having a large number of newbies running around the TBP internal.
What I was thinking was more along the lines of making a smaller campaign. As you spot FREDders with talent you can graduate them into TBP proper. Rather than getting FA to make the main campaign it acts as a minor league for you to scout from. (Not that I'm putting down the FA campaign. The quality of the work on some of the FA missions rivals that of any hosted campaign)
In many ways I think a FA for TBP would actually be more successful than the original has been. Unlike Freespace 2 there are a limited number of TBP missions available (even after raider wars is releases) so you're going to have a lot of mission hungry people willing to playtest
That's always been the big problem with FA, getting people to playtest.