I understand this wasn't directed at me but seeing as I had a similar reaction I hope I can give you some explanation of my response.
Firstly however, I'd like to apologize for the tone of my response below. While I stand by my post's general idea I feel it was poorly worded and came out unnecessarily hostile and combative, along with overly dismissive of your point of view. I'm going to leave it up unedited if for no other reason than to serve as an example of how not to engage in these discussions. In particular, I really shouldn't have made any assumptions about your specific background and again, my apologies.
The exact reasons why I disagreed so strongly with your post are proving difficult for me to illustrate beyond what I've already written. In essence, by painting the act of self defense as being morally or ethically ambiguous, I feel that you are essentially dismissing the experiences that those like myself, who have had to endure violence first hand, have had. I fully accept that I may be misreading your intent here but it comes off as somehow equivocating a defensive response to violence with using violence to prey on others.
Its also upsetting to me because I run across similar sentiments in my daily life that I find troubling. While I consider myself fortunate to both work and socialize with people of many different classes and races I find certain attitudes held by most of those who had the luxury of middle-upper class upbringings regarding being poor to be problematic. I understand this may not be the case with you and I overreacted.
All too often however I come across people espousing views on what it's like to be poor or be surrounded by violence without ever having been poor or surrounded by violence. It comes off as dismissive of my experiences.
It also showcases the problem of racial and economic segregation that is becoming increasingly widespread in the US whereby the burden of being poor and living around violence is increasingly being cordoned off from the rest of society. To me this is expressed by views such as yours that hold self defense as morally ambiguous. It's telling that not a single person who I grew up around would ever consider their right to self defense, even if using deadly force, to be problematic. The only people who I've ever heard espouse these views have never encountered violence at all. I understand that this may not be you, and that there probably exist people who have been victims of violence and still view deadly force as unjust, I've just never met any myself and this surely distorts my perspective.
I'm unsure if this post makes a coherent argument that explains my views succinctly but I hope it helps.
Either way, sorry about the tone of my previous comment.