In a furball situation there's no such thing as pick, it's all for all and you're just clearing countrymen's 6. In a 1 vs 1 situation if your ally is not asking for help and you're just going in for the shot then maybe that's a pick.
But yea, I don't have any regret for shooting other people down using BnZ style in a furball. If you have poor SA and you get shot down, can't squeak about it xD. I get shot down in furball and 1 v 1 all the time because my SA wasn't good enough, and I just walk away saying damn I guess I didn't track that guy.