Well, in the general public yes.
Would you have shot either of them? If so, which one?
Well first instinct would be to shoot the guy doing the strangulation. The knee jerk reaction would be to shoot him. However, ideally I would handle the situation by drawing my weapon and instructing the strangulation to stop. And call the police while keeping them both at gun point until the police arrive. I'd have to intervene in some way because I couldn't live with myself knowing I let someone get murdered. But if I got a big F U from the guy doing the strangulation and he didn't stop and the victim is begging me for help, yeah I would've blown the brains out of the guy doing the strangulation.