I think he's right. It doesn't say anything about playing the card you drafted. What would be the point of drafting the card if you immediately have to play it?
I completely agree with David. The drafted card goes to your hand. You can prepare it, or keep it in your hand for later.
The build is an intrinsic effect of the event card. There are plenty of other event cards that instruct you to build, even without drafting first at all (The 17th plan for example).