Iron Man is distracted right there! Turn his suit off!
Did he scour the internet for evil plan suggestions and pick the most sarcastic one?
When they finally "kill" Ultron, it's mentioned that Vision has blocked him from the web so he can't send his consciousness out. But during his town-floating rampage, he had access to countless storage spaces on which to upload a copy of himself. Saving your work is something a 60-year-old divorcee learns on their first day of typing class; one would imagine the smartest thing on the planet could manage that level of redundancy. For a guy who loved bragging about being everywhere and limitless, it seems like he's quite limited, and pretty much ... right there.
Why does a robot need to sit?