One could argue that advocating against firearm control and regulation has resulted in significantly increased societal harm, which could also be identified as not fair, if not even evil/hateful, especially from those who have directly suffered from it.
Of course two wrongs don't make one right, and people can be more classy than this, but it's a totally understandable sentiment and response.
None of my claims disagree with what you just said. People posting the "gotcha" also likely don't disagree with you.
In fact, I suspect that most hate firearm-related violence and have worked to stop/curb it, and were opposed by Kirk who undeniably unfairly got a taste of his own medicine.
Of course two wrongs don't make one right, and people can be more classy than this, but it's a totally understandable sentiment and response.