In general, it seems that in judging between the actions of a surrounding, partially armed mob and those of an individual trying to escape same, the benefit of doubt would lie with the individual more than with the mob.

One could be forgiven for suspecting that the operative factor in the DA's zeal to charge murder under these facts is the political slant of the particular mob. If all other facts had been the same save that the "assault rifle"-carrying protestor had been participating in a rally for Blue Lives Matter or some other unacceptable cause, it seems inconceivable that the Austin DA would pursue a murder charge against the shooter (who would perhaps be something of a local hero).