Replant?  It's a 24-row drill.  and he is missing 4 rows out of 24 - 2 rows on each side.  That means he has 83% stand already.  How would you replant?  How much more seed would you put down?   Wouldn't you be crowding the bulk of the field where he already has a stand growing?  I would think that replanting the whole field at an angle would cause more problems than what he has already.

Personally, I think the rows that are on either side of the gap are going to compensate and shade over some of the gap.  It won't be 100%, but that 83% stand is going to perform more like a 90 or 95% stand.  Personally, I would let it alone.  Call it learning experience.  Learn how not to make the same mistake again.   But replant?  Not me.   But that's my opinion.