Undesrscores how powerful Google is. To many people internet is what Google shows to them. Though its a slippery slope, If the peson who is requesting for changes is liable for those then Google should comply. DMCA also has similar provision.
It's a difficult problem to solve both because of Google's primary goal (provide an accurate representation of what people are looking for) and the difficulty of deciding who's actually "responsible" for a given category of content.