I don't know why this is even a question. It states specifically in the Trader FAQ that "if something would have happened due to gaining the other card, it does not happen, because you did not gain it." Open and shut case right? You never gained a card from ironworks so you never get a bonus.
Ironworks doesn't say "If you do..." - i.e. there's no explicit contingency stated on the card between gaining a card and getting a bonus. The ruling hinges on what the word "it" in the 2nd sentence refers to, and Donald has most recently ruled that "it" means "the card you gained" (rather than something else, like "the card you chose to gain").
It doesn't have to say "If you do..." - 'Gain a card' means 'gain a card' not 'intend to gain a card' If you never gained a card due to ironworks then you get no bonus. The explicit contingency is stated in the BASE game where gaining a card is defined as taking a card from the supply and putting it on your discard pile. (of course with other, newer cards, where that card is placed can differ, but that has nothing to do with this confusion.) Trader doesn't say to gain a card, fulfill all actions and reactions based on that card, then put it back to the supply and instead gain a silver. It states "When you would gain a card...instead, gain a silver" meaning you never gained the original card and all reaction based on gaining that card are no longer in effect. And that, I believe, most accurately reflects Donald's latest interpretation.
