Sorry, I was misunderstood. To clarify, I was referring only to our work (http://www.cs.utoronto.ca/~phillipa/sbgpTrans.html), where security does play a small role in the route selection process (after LocalPref and AS-PATH length), and not to the BGPsec spec. The reason why we assume that security affects the route selection process is because otherwise, even an AS that deploys S*BGP, remains vulnerable to attacks. To see why, take a look at slides 10-13 of our NANOG presentation (http://www.cs.bu.edu/~goldbe/papers/Goldberg-TransitionToSBGP-NANOG.pdf, video available at http://www.cs.utoronto.ca/~phillipa/sbgpTrans.html). The basic idea is: if an AS prefers short paths over secure paths they'll be just as vulnerable to path-shortening attacks with and without S*BGP.