Shit. This might be the best poster.
Tony's response was based on pure emotion. Any normal person would have reacted in the exact same way. Steve withheld information from him. 'Did you know? Don't bullshit me Rogers, did you know?'. Bucky's innocence is irrelevant. Anyone who has ever snapped or exploded in anger can relate to Tony. Never had a chance to say goodbye to his dad, lost his mum who he was close to. And their killer is right in front of him. Also taking a break from Pepper and his best friend is in critical condition.
If people can't see why Tony wants Bucky dead after all that, then maybe they're emotionless robots.
There is a huge difference between understanding why Tony reacted the way he did and thinking what he did was right. I dare say I understand why he lashed out better than most do. That still makes him wrong, though.
His parent's killer isn't in front of him; just the man who was forced to do it for the actual killers. And he knows that. And that's why the "any normal person would've done that" point doesn't hold any water. That just means most people would've knowingly tried to murder an innocent man, not that he's innocent. It's a false argument. Be like me excusing Killmonger of all of his crimes just because I completely understand where he's coming from.
I pity the fan that doesn't.