Why is that a shame?
SYG advocates tend to act like a person isn't allowed to defend himself in a blue state, but that simply is not the truth. I don't know these guys personally but it sounds like a reasonable overview here:
Basics
Under Massachusetts law, if you are attacked or reasonably believe that you are about to be attacked, placing your physical safety in immediate danger, you have a right to defend yourself. However, you are obligated to take reasonable steps, if available, to avoid physical combat before resorting to force. Moreover, you are not allowed to use more force than is reasonably necessary to defend yourself. You may use deadly force – force intended or likely to result in the death or great bodily harm of an assailant – only where you reasonably believe your assailant poses a threat to cause you great bodily harm or death.
Duty to Retreat
Unless you are within your home or a place where you are temporarily residing, you may use physical force in self-defense only where you are unable to escape without exposing yourself to further danger, summons immediate help, or hold the assailant at bay until help arrives. Under the Massachusetts Castle Rule, you are not required to retreat from your home or to attempt to avoid combat with an unlawful intruder. You are allowed to use deadly force on an intruder if you believe he may kill or badly injure you or another person within the home or dwelling.
Resorting to Deadly Force
https://www.relentlessdefense.com/what-should-i-do/right-to-self-defense/
A jury ultimately decides these cases, so if someone punches you, you're not going to jail for punching them back. However, you're probably going to jail if you lay them out flat, straddle them, and hit them until bystanders pull you off. Reasonableness is the key.
Juries will also consider body size, etc. If a big man punches a woman and she shoots him dead before he can swing again, she's probably in the clear.....unless he punched her, raised his hands, and backed up 10 steps. You just can't go overboard. If this shooting happened here, that guy would go to jail.
I really don't understand the need for SYG laws. They tend to protect aggressors much more than defenders.