"Instead of doing this, the Dragonborn can choose to kill Astrid."
I actually did try to kill her, her health dropped, but after a moment she recovered and did NOT die. Apparently Astrid has been made essential and can no longer die.
A strange bug, when Astrid jumps off the shelf and you kill her this may make her "essential" for a moment and not kill her. Tried it twice and killing her was now no problem.
