BFR as a project is out of touch with the current affairs at Tesla and SpaceX which means that there is basically no negative sentiment that can be generated from asking questions about the topic or their answers.
A general AMA however will likely touch about things like the failure to support Autopilot 2.0 hardware on schedule, Model 3 delivery delays, Falcon Heavy delays, and those are just the light stuff.
One does have to wonder why is there an AMA on the only detached and "universally rosie" subject just as Tesla announced layoffs.
While I don't think it was planned, I do have a strong suspicion that the AMA was intentionally focused and the mods were asked to enforce question rules (and looks like more strictly than usual even based on previous Musk AMAs).