Volunteering and helping other people - can it be a symptom of ptsd?
No - not directly. Its more complicated than this though. Sure, avoidance could be an aspect, but helping others is not an avoidance strategy. Anxiety however is manifested by the over-doing aspect. Put too much pressure on oneself, the anxiety then spikes symptoms, collapse, repeat and rinse. Helping others can make a trauma sufferer feel good about themselves.
Many people who have endured trauma want to give back. If giving back to others is a symptom of anything, it is of enduring an event to begin with, understanding how hard it can be, then wanting to make others lives a bit easier if they can.
The avoidance aspect can be the excessive aspect, being over-doing it to the point of breaking yourself. Repeat and rinse. But what is a person avoiding is the question?
I did this exact thing with this exact forum, when I started it many moons ago. I helped myself, I helped others, at the expense of my own emotional and physical capacity, relationships too. I avoided a marriage which was another pressure on me, to help others instead. Acknowledging our limits is the aim, I think. Yet saying that, workaholism is a coping trait for trauma, however, it should not sacrifice healthy aspects of our lives.
Workaholism at anything is a fine line. Healthy, yet unhealthy, and is like walking along a fence itself, thin, and you easily fall one way or the other.
Many a trauma therapist endured violent, PTSD level, trauma, to put them on their path to help themselves and others.
Nothing is every simple with trauma, and not within the broader scope of each situation.