I'm assuming your points are: 1. John Galt used his talents to make the world suffer. 2. John Galt is obligated to use those talents for the common good.

1. In the sense of actively destroying things, nowhere in the book. Maybe he goes kicking around puppies somewhere off the pages, but he does nothing of the sort anywhere in the book. Ragnar Danneskjöd does, but that situation is hard to judge given the details in the book.

Galt did know that he had (assuming you mean the motor), the wherewithal to make the world a better place. But, a. He believed that doing so would only improve conditions in the short term, since the system in place was naturally errosive. Changing the system and then bringing forth his idea would provide longer term benefits. b. That assumes he was out for the common good. He wasn't. Doing what you proposed, namely comercializing his invention and "making the world a better place" would have led him through the same agony that Hank Rearden and Dagny Taggart went through, trying to keep things together when they were clearly falling apart.

2. I disagree with you that anybody is obligated to do that.