Honestly if that ever happened to me I don't think I would re-pledge and I don't think you should for this organization either. I think you should go back and ask them for a clear answer as to why they didn’t want to initiate you, and maybe consider going with an organization that better suits what you want.
All of the posters ask valid questions and two things come to mind.
If grades are a factor, then there is no recourse, and if they are not then he should talk with his big brother to see what the problem is. If it was something other than grades, then he should rethink about going through an entire peldgeship again.