I agree that it is important to look at homicide rates rather than rates of gun deaths. (Relevant) arguments against gun restriction are basically that, first, it isn't practical to significantly reduce the amount of gun ownership amongst the prone-to-impulsive-violence population, and, second, that if you did other deadly implements abound, especially ones that magnify strength disparities that likely correlate with being violence prone.

Looking at just gun death rates after restriction can argue against the first (given other variables controlled) but murder rates are the more important stat and could update both hypothesis one way or another.