Although I'm unwilling to die trying to rescue someone, the above actions are not significantly threatening. A mask is nice, but not required and I won't immediately die if someone pulls the reg out of my mouth. I have a spare, and sometimes two.
Those actions are very much threatening and I don't understand why you would think they aren't. While not necessarily life threatening, it is certainly not a position I would want to put myself into. We do not know what this woman's frame of mind was and I am not necessarily defending the actions or lack of from the DM, but I guarantee you, if someone does not want to be rescued, I am not going to risk my life to save someone who doesn't want to be helped. It's not like we are in a position to talk this person through the problem.
Unfortunately we never seem to be able to end up with all the facts. This thread will die off and we may never know the true story here.