This I like. I like the idea that Pym's most successful scientific contribution and a breakthrough becomes a massive threat to life on Earth. But also I want to see it be presented to also show that Ultron is Pym's dark side given form. Pym has very real mental problems, and secretly resents his friends, his team of Avengers, his wife, himself, his colleagues, etc. And when he scans his own mind for the blueprints to Ultron's brain Ultron becomes sort of the evil version of Pym. I also think Ultron would continue on and along with his upgrades he would upgrade his mind and formulate his own hatred and reasons for them. And Pym being like his father, Ultron is like the son who learns to be full of hate at his father's rivals from his father. Pym blames himself and feels more guilt than he is actually blamed for. He also would feel such guilt because all his doubts, fears, hatred, resentments, anger, sadness, etc, have been made public in a very big and public way. Plus Pym already suffers from real mental problems like anxiety, stress, schizophrenia, etc. So this wouldn't help him.
So its like Frankenstein's monster, Dr. Jekyll and Mr. Hyde sort of, and a father and son story.
Bring in the idea that Ultron creates Vision, and Vision sees the flaws in Ultron's hate and turns against his own father, and it becomes a generational thing. The grandfather (Pym) inadvertently passes down his hate to his son (Ultron), the son (Ultron) passes down his hate to his own son (Vision) who listens to the grandfather who has changed his heart. Ultimately Vision would in a way redeem Pym.