He asked which he preferred, sacks or pick 6. Bruce indicated he preferred sacks.
From a personal pride standpoint, the QB has to make a mistake to get an interception, so while it has more impact for the team, it is more about taking advantage of 1 person's mistake. A sack however, you have to beat the lineman standing in front of you and then go and beat the QB and drop him. You beat 2 people to make it happen, a much more physical accomplishment, which would appeal more to some people.
I don't fault him for the answer and I don't think it says anything about his mentality other than he prefers sacks. He also stated that it is all about the wins in another discussion, so it isn't like he's going to trade one for the other, he's going to take the opportunities as they present themselves.