So obvious. So so so very obvious. What does it matter he's "surviled"? "Hey Tony shit is fucked" "Ok, Cap" and now he's wearing an Iron Man suit before SHIELD/Hydra can even power up the servos on the missile to point it at his house. Stark Tower doesn't have point defense systems? Iron Man all suited up doesn't give two shits about missiles.
The only reason to avoid contacting him is if you think he's in on it. That would've been cleaner. Have Winter Soldier and his goons carry weapon marked with Stark Industries or something. "I thought he was done making weapons!" "Maybe we don't know Tony Stark very well at all...".
The script was bad.
Maybe Iron Man just didnt know? SHIELD/HYDRA controlls the media. If I were HYDRA, I would not really let the media cover up the actions of my killercommando, who was sent to kill the legendary hero of world war 2 and defender of earth against a alien invasion. And I wouldnt say them that I equipped my three brand new helicarriers with death missles. Anyway, I dont care. The Movie is about Captain America, and no one beside him has to show up.
And I say it again: In the comic books, this happens all the time. Heck, even in the comics the whole Marvel Universe is living in New York and even when there is something on a bigger scale than a heist, there is as good as always just one hero. Maybe a team, but never all the heroes come together for this. Because its a Solocomic (or movie in this case) and not called Captain America and lall Avengers, who just cant show up, because people in the internet made up stupid complains: The Winter Soldier.
When you cant accept this, dont watch Superhero Movies. Its called suspense of disbelief or something like this.