[xattt]

What about flight laws/flight control modes that prevent this thing from happening?

Unless the aircraft was flying in a degraded state, these limits are supposed to prevent the aircraft from suffering damage during flight.

[icegreentea2]

Briefly going slight negative G will not damage the airplane.

[Vecr]

It's a Boeing, that's not really how it works. What airplane refuses to let you do negative gs anyway?

[p_l]

Both 777 and 787 are full fly by wire, with the latter being unstable without computer help due to trimming of control surface sizes for greater fuel efficiency.

[Vecr]

For some reason I didn't think it switched laws, it was just on or off. Maybe that was for the 777 instead?