Better question would be how many babies did he save from being butchered?
It's a pretty safe bet that the answer to that question is zero. He certainly didn't save any babies by killing a police officer. And even if the civilian (or civilians - I've seen reports of two civilians dead) was an abortionist, the effect on the total number of abortions performed will likely be zero.
Not to mention that an incident like this will likely increase sympathy for PP, and possibly increase donations from PP supporters.