While 0.3g's laterally is a lot, with normal onset it is no where near enough to rip the vertical off a healthy airplane. If there were other prior damage it might do it. There have been questions about design load spectra on an unidentified Airbus type but I can't know if is a contributing factor here.
So far the most excessive thing I've seen is the amount of talking the NTSB is doing at this stage of the investigation. Now THAT's extraordinary.