Burning down porn shops and shooting abortionists are crimes only in the sense that they are illegal.
The action is forbidden, but it is not unjust.
But everyone does have a right to be treated in accordance with the law. Even in the case of a murderer, e.g., an abortionist, he has a right to a fair, speedy, and lawful trial by a jury of his peers. One who "takes the law into his own hands" by killing him is in a real sense committing an injustice, both against the abortionist and also against society whose social coherence depends upon justice being administered through an orderly and hierarchical system. Therefore such an action, even if it provides some benefit to society, can hardly be considered laudable or unworthy of at least some punishment.
This also suffices for the case of Geoghan.