After the tournament, there was some major discussion about the importance of First Blood as a secondary objective in The Emperor's Will. Some argued that it ended up being a game of taking First Blood, and then the leading player would camp their objective hard. The players thought perhaps the game should be altered to prevent that strategy.
My opinion of this has not changed; I think First Blood is certainly a wonky objective. Without a doubt, it is an objective that favors the player that goes first. However, I do not see a justification that makes this particular mission worthy of avoiding First Blood. Every mission has First Blood; it is a cornerstone secondary objective in 6th edition. Frankly, aiming for First Blood and camping is perfectly legitimate.
If a better secondary objective comes up, I would consider using it. For the time being, First Blood will have to do.