Yes, but my point was that we can deal with the heavy toll. Thus, saying you would take an action that might be very risky as you couldn't live with yourself isn't sensible.
For extreme example, would you prefer to be eaten alive rather than going through some cognitively behavioral therapy?
Taking the action to save the child and be willing to risk your life to save the child is a viable decision route. Saying you didn't act as it was already too late makes sense also. Not acting because you fear for you own life and/or you didn't want to impact your family (thus valuing the child -who may be too late to save) is a viable decision path.
Saying you will take on high risk because you will get a stress disorder, doesn't work for me. Thinking about it, it might be that one feels that others will think ill of you for not acting and that's the subtext of that kind of statement.
I have a nice presentation on altruism in bystander interventions that I can give.