The outcome is the same.
Imagine how a slave would feel if someone said, "I'm not pro-slavery, I'm pro-choice." I'm sure that would be encouraging. The buggy banner would read, "If you don't like slavery, don't own one."
Personally, I'm against child abuse, but I could never tell someone else not to do that because I would be imposing my values upon them. I'm just staying above the issue and allowing each person to make his/her/zir choice. That way, I can sleep well at night, knowing that I'm maximizing personal freedoms and not infringing upon the rights of others re: their own property.