Firstly I believe that it is the human element in this situation that is the weakest link, customers who are going to make a purchase online especially a big purchase like a Montblanc pen should spend some extra time and care in researching where and who really is taking their money and other information.
In my opinion Google should not be held responsible, they have been cooperating with Montblanc in solving this case and are doing everything in their power to help. You cannot expect Google to give out details of their customers with just a request, going to court makes sense as it makes the issue official and gives Google the legal power to disclose the counterfeiters information and thereby exposing their identity.
If Google takes anymore steps to curb freedom in order to prevent counterfeiters the Google search will not be the free utopia that we all know and love.