Yea, I actually played with that sentence a few times. I thought about making it clear that Firefox and Thunderbird weren't called Firefox and Thunderbird when they were part of Mozilla Suite... but the codebases are the same, I think. Sometimes you have to know where to draw the line, to keep things clear :)
Neither Fx nor Tb were part of the app suite--they were both offshoots that, at the time, really violated what the project was aiming for. The story of how Firefox came to be and roguish it was seen within the organization at the time is interesting.