I would find out WHY, in detail he is opposed to the skip. We skipped 3rd last year and went into 4th and it's been great! My child wasn't opposed though, and as a pp mentioned, if the child is against it, almost all bets are off as far as the IAS goes.

I would sit down and talk about the cons of it and push the pros and see if you can't shed some light on those fears (whether he denies he has them or not, they are probably there.)