They are a huge allowing factor. UK has a rate of violent crime almost double ours and a rate of homicide not even half of ours. Firearms are vastly more lethal then hands and feet and contact weapons. Studying the proximate causes of violence with firearms is certainly legitimate.
In the Czech Republic most private citizens can own guns, they have owner licensing and registration, they had to in order to join the eurozone, but other then that there is little restrictions on what a citizen can own and any citizen can carry a concealed weapon if they have a self defense license, which is issued to all who qualify. Shall issue if you will. AR-15s, saturday night specials, handguns,SBRs, standard cap mags, all legal with no special restrictions.
In Czech Republic violent crime is very rare and so is crime committed wi firearms.
So no firearms are not a casual factor, but the differences between two progun countries (relatively speaking) show that there is a contrast and studying the differences of gun violence in our country when compared to ones with similar legal restrictions on guns is certainly legitimate, and no where in the lecture did I hear the lecturer advocate new gun control laws...