Of Redemptive Heroes and Family Values Villains (джен)

Why exactly is Tony Stark a redemptive hero? Watching how he's treated by his fellow Avengers you'd think being a former military contractor is a sin far in excess of being former terrorist, a former assassin, a former war-mongering prince, but that can't possibly be right.
And the Vulture's operation of making weapons for criminals, only in looney-ville would that be considered no different from making weapons for a legitimate government, right?