I see what you're getting at SASless however, the profile you are talking about would not have been possible with the nav kit the Vulcan was carrying on Black Buck.
The navigational inaccuracies that were part and parcel with the nav kit carried on the Vulcan & was quite a handicap. Bearing this in mind, the crew did well to find the Island, never mind the airfield!
Attacking with the 35 degree profile allowed for a greater degree of error on the bomb aimers part. This is in contrast to the 'down the centre line' approach, which would have only allowed an error in aiming equating to half of the width of the runway.