The ATF report lacked facts and evidence to back the decree up because it's not important to what they want to accomplish. They want to set a precedent for the "banning" process as a model for use later on. Labeling things as "cop-killers" whether a weapon, a type of ammunition, or whatever makes it easier to get the uninformed to go along with it.
For myself, I have yet to see anything in the last 12 months that would indicate this Administration gives a crap about the dangers facing LEO's, unless of course you're referring to members of Obama's Alphabet Army (BATFE, IRS, EPA, etc..).