Making it more difficult to find may just be one portion of the strategy - no doubt the location of the images is reported to the relevant authorities, and then it's their job to take up the issue. Perhaps reducing access to the material will reduce the ability for people that search for it to find it, which may reduce the number of cases where the activity escalates to direct abuse. Maybe it'll increase the number of abuse cases as they're unable to relieve their desires and turn to local sources.
Although I think that people abusing children should be outright shot. I have trouble following the logic of the above statement. There used to be a under the counter market for such material and big bucks could be made with it. (The internet basically killed that market, hopefully.) Here there was a real economic incentive to produce material and demand encouraged production. But now, thanks to police work, there is little to no commercial trade of the material. Because the material is such a hot potato, people searching and distributing the material are forced to use means of strong anonymisation and thus no economic transaction can occur. I think most CP created nowadays is distributed along the same lines are people uploading their private videos to porn sharing sites.
The service by Google is very useful to prevent from services hosting the stuff. Since hosting stuff, even for a very short period of time is always bad PR. What Google builds is basically for PR, for Google and everybody using it.