Well he is a "bad guy", remember the guy is a serial killer that targets State officials; crime with political intent makes him a terrorist.
Well what do you expect? The military obliterated his entire family before his very eyes of course he's gonna turn into a terrorist. Based on his circumstances I can't view him as a bad guy.
Justice comes from vengeance. What Scar is doing is the same thing as Hughes wanting to kill Envy for killing his brother (I'm assuming he kills him eventually but I haven't made it that far yet).
And what the black dude told Edward that they really screwed over his people and Edward responds with 'well one of your people killed my friends parents'... BI*TXH WHAT?

? That's not even CLOSE to the same thing! That's not equivalent at all PERIOD.
No but yeah your second paragraph is why the show is so good