Back when the Spartan program was created, 'terrible fate' was merely secession. I dunno if this fate overrides the purpose...

: What's so bad about being a Spartan anyway? Who wouldn't want an absolute
: purpose in life? To be the best at something. To inspire by your mere
: presence. To have the body of a god and to be able to move like the wind.
: Choice is overrated sometimes, I think

Sometimes, I tend to agree, even if just for the sake of narrative. In John's case (according to Nylund), we can clearly see he nigh-volunteered there. Maybe that was taken in consideration on the profiling (acceptance of the situation, I mean).