I think the wording for the "Ho! Tom Bombadil!" boon (our first event boon) is likely:
Setup: The first player adds this card to his hand.
Response: Add this card to the victory display
and remove it from the campaign pool to cancel
the "when revealed" effect of a treachery that was
just revealed from the encounter deck.
It might be card instead of treachery. We've seen remove from the campaign pool before, with Phial of Galadriel (look at The Grey Company podcast on facebook for Gencon spoilers if you haven't seen it yet). I think this is a great and thematic idea. One of the dangers with boons, especially those with the Setup keyword, is that the players will be incredibly powerful by the end of the campaign. (The opposite is also true: if there are many burdens with surge that the players can't avoid adding the campaign pool, the encounter deck might overpower the players before they get going.) Ho! Tom Bombadil! is powerful because it's free and you don't have to wait to draw it, but you only get to use it once in the entire campaign. (As a thematic player, I want to use it during Fog on the Barrow Downs, and I want to use Phial of Galadriel against Shelob.) Old Bogey-stories, the boon from The Old Forest, will have a more significant impact on the campaign because it's a Setup card that can be used every game to provide a nice benefit. (If you didn't take Gandalf's Delay as a burden, you can mulligan after playing the best card in your hand.)
I think the designers are aware of these dangers, and trying to avoid them. That's why Mithril Shirt and Glamdring each cost resources, whereas they were free when they were treasures in The Hobbit expansions. Especially if we're required to have a 50-card minimum deck without counting boons, the designers can give us many boons in one box (the key items received in Rivendell and Lorien), without making the players too powerful. Also for burdens, we've seen in Flight to the Ford that it's possible to minimize adding burdens to the campaign pool, but at a cost. Based on the spoiled Council of Elrond quest card, the decision to shuffle Lust of the Ring into the encounter deck may also add it to the campaign pool. This provides fun, tough choices for players.