My point has more to do with whether the mission is as crippling a handicap as many assume.
While it is true that most skill players are African-American, a majority of linemen (especially O-linemen) tend to be white or polynesian. I would think that with that demographic, BYU should be able to put dominant lines together.
Additionally, although a rugby player may be poorly suited to the WR and DB positions, they would make great RBs and LBs, as-is. I don't think recruiting is the issue at BYU - it looks to me like development and coaching are larger concerns.