This is a nice description (i.e "where is the limit on this type of action?") of a reason why this approach is low on the list, and why ideally we would solve it with one of the other options.
You don't want to give people "moral license" to do this broadly, but we've hit a point where there are no options available that don't have downsides. Stated another way: Taking no action can also be unethical.
Man, I really emphasize with this, and that immediately raises my "motivated reasoning" hakles. There's a lot of people in America with deeply held views that I strongly disagree with, and I would be very worried if they began taking matters into their own hands; to pick a hopefully-uncontroversial example, bombing abortion clinics. They, too, would say "to take no action is also unethical". The purpose of society is to arbitrate these kinds of disputes...
I agree but will point out that abortion is an example of policing activity that does not affect oneself. Adding an additional clause reflecting that aspect seems to fix many of the issues that might concern you.